Another question: If you're good at managing complex projects, have a lot of discipline and have no obligation to obtain any credits or take part in any other uni courses, how realistic do you think is it to completely finish a PhD in 3 years? As a fresh graduate I'd never considered this possible, but with a few years of work experience and working on complex, long projects I do wonder whether it would be possible. What if you earn a bit of extra cash through tutorials and the likes? After all, this time comes off your research time.

Yes, it's possible. I know one student who did it, and a few who submitted within 3.5 years.

By completely finish, do you mean viva and corrections done? If so, then you'd have to be submitting around the 2.5 year mark, and hope for no more than minor corrections.

What chickpea said.

Also the problem with a PhD is that it isn't just dependent on how hard and quickly you work. If supervisors don't give you prompt or proper feedback, then you'll just be waiting for ages, or have to keep submitting the same chapter over and over again (which takes time). Don't underestimate how important supervisors co-operation is for a finished thesis.

I am surprised that anyone would require to submit a chapter to their supervisor "over and over again" at the end of their phd. I expect my supervisor to read my thesis once and once only before submitting and my first draft to him will be of a quality I believe is absolutely 100% ready for submission. My opinion is that after my phd is over I am a research-ready independent researcher who doesn't need help to write reports. Is it really common for people to require this much support at the end?

It depends on how you get on. If you get plenty of results there is absolutely no reason to require more than 3 to 3.5 years. Others stress the importance of your supervisor and maybe that is common but the most significant thing I found was to ensure before I start the phd was that I was fully up to date with my undergraduate level of education. If you think about it this makes some sense. If you have a 2:1 then you have understood only around 60% of all of the undergraduate material each year on average and this knowledge will be heavily weighted towards your final year. This means you will likely have forgotten much of your first couple of years. This, in my purely subjective opinion, is the most serious flaw of people starting phds and one of the reasons for people taking 4, 5 and even 6 years to complete. Of course it would be helpful if people were told this before they start but perhaps supervisors expect you to revise during the summer before you start. My phd is in the physical sciences and to be honest I don't know how anyone can complete a phd in three years if their undergraduate level understanding of their own subject is weak.

So in summary, it is possible to graduate before your funding runs out but you need to stabilise your undergraduate level of understanding as a priority before you start.

Plus sometimes it's not the student but the supervisor who insists on seeing things again and again. Sometimes the work is completely fine, but supervisors insist on checking revisions.

And with regard to undergraduate stuff, that's great in an ideal situation, but what if you're approaching a PhD following a break from education or changing subject area? You can't relearn three years worth of work over a summer, plus half of it won't be relevant anyway and I don't think any supervisors expect a student to know their u/g stuff backwards - supervisors don't know it all anyway, particularly when it's not in their subject area.

Fair enough on the first point but I would strongly resist this. I would want to know why I wasn't able to do what he wanted after being told once. If he kept changing his mind there would be a very tense and terse discussion at the second draft.
I appreciate what you are saying in your second paragraph but it is also completely irrelevant to me whether my supervisor expects me to know undergraduate level work or not. I would ensure I had the background to allow me to succeed before taking the position on and I strongly believe that those who don't seriously risk over-running their funding or failing to succeed. If I didn't have time to get a good grounding before starting I simply wouldn't do the PhD. You would have to be absolutely insane to attempt a PhD in an area where you were weak on the undergraduate level. The PhD requires a good background. I either accept it and do something about it or ignore it and struggle.

This is my PhD. Not my supervisor's. Not the university's. Mine. I will have to sell this for the rest of my career.
Therefore I have a mindset that everything is my personal responsibility. When I interviewed for this PhD I also interviewed the supervisor and we had a frank chat about what kind of supervision would work and would not work for me. Had we not come to a mutual agreement I simply wouldn't have started the project and would have found someone else to work with. It is very important that you enter these arrangements from a position of strength. If one party is dominating the other then it will never work. There are hundreds of posts on this forum highlighting what happens when you don't do your groundwork on your supervisor. It can mean career suicide. In my case I made sure my supervisor knew I didn't want to be controlled over my working hours or working location. Neither did I want him in my office routinely checking up on me unless I contacted him for help. I also was very clear I wanted to write my own papers and that I didn't see him as being my spell checker. Of course all of this is within reason (I let him know when I am taking time off or working from home) and fortunately he wanted that arrangement himself so this works for us both. I am now writing up and expect to finish before my funding runs out.

For me this is a mindset thing.

That's all great in an ideal situation and if you're luckily enough to be in a position to choose between different PhD projects initially. Not everyone is.

Luck?
The harder I work and the more I think and plan ahead, the luckier I seem to get.
I am not a big fan of using excuses for my failures.

I submitted my PhD after 4 years, I did lots of teaching and published quite a few papers during this period. It definitely helped getting a job afterwards, so it's not a waste of time.

I would have finished earlier, if :
1. I had knowledge of a statistical software that would allow me to be more efficient with data management;
2. I was stronger in statistics, and knew from day 1 what's the best way to analyse data with complicated structure.

I would have taken longer if
1. My supervisor was not helpful in practical matters, (like I need this equipment NOW)
2. If I wasn't already quite comfortable with scientific writing

Well personally I think there's a whole lot of luck involved in people's success. People can do all the planning they want, but if they are not in the right place at the right time, or don't know they right people, then it doesn't make much difference.

What you are calling luck, I call opportunities.
Opportunities occur literally all the time. Most people miss them.
The key is to be open to opportunities, to have the eye to spot them, the background to exploit them and the courage to try things. Most of this is under my control.
You are of course perfectly entitled to call this luck but like I said, everything I have ever achieved has been largely down to my efforts. To suggest it is simply nothing more than pure random luck which anyone else could have succeeded in exploiting is not something I agree with.

I will take one example from your post. Not Knowing the right person.
If you know your field you already know who the right people are.
So make contact with them or find someone who can do this for you.
There is no excuse for not at least trying to do this, failing to land a job with them and subsequently blaming "bad luck" because it is nothing of the sort. It is bad preparation.
Am I persuading you?

I certainly agree with the adage that "the harder you work, the luckier you get" but there are still a whooooole heap of things that can happen out of your control in a PhD outside of hard work/opportunity. I have a weird curse of my supervisors falling pregnant.... so three of my four supervisors in my honours/doctorate have gone on mat leave very close to me submitting! Yes, I am entitled to get alternate supervision but ultimately this is not the same as supervisors who know the work and has held me up. I also ended up in hospital having cancer treatment during my first semester, which set me back as you can imagine. There are SO many other examples I can think of among friends, which have nothing to do with the attitude or efforts of the student.

Not saying these challenges are insurmountable, and of course a resourceful and resilient student can do a lot to bounce back from these challenges. But sometimes things happen that are out of your control and its going to delay your candidature. That doesn't mean you are a bad student or have a bad attitude. It is not the end of the world to take longer than 3 years and certainly doesn't make you a failure.

Anyway, it's really awesome that everything you have encountered has been a matter of hard work and harnessing opportunities, and that you plan to make sure you submit on your terms regardless of what your supervisor wants, but not everyone is in the same boat as you.

Agreed, teegs - there are many people who are just as hard-working and capable as anyone else, but who don't experience things in that linear 'work>result' way. I don't think anyone working through a PhD is a failure and I would like to see us give each other a break.