Hi
I'm struggling to get consistent advice at my university, incl my supervisors and I dont know who to trust.
At the start of my PhD and up until about 1 month ago (I am 3.5years in), myself and my supervisors have thought I would do 5-6 studies, so that would amount to 4-5 data chapters, with some chapters having 2 complementary studies in.
However, I feel a little behind due to stress-related illnesses this year, and my data coding has been really slow (because I was ill but also because it was a huge task). I requested an extension and all supervisors and student advisor agreed I should have one. But then 2 weeks ago, I was told it was not even possible to get an extension under a 4-year programme. My supervisors told me not to worry, that I could just do one more study and it would be fine (so that would be 4 studies in total).
I feel the advice and supervision has been inconsistent throughout my PhD, and I find it difficult to trust that I will be successful in getting my thesis with cutting out 2 studies...I mean, supervisors should have an idea of how much is required, and then stick to it? So is it that my supervisors wanted to squeeze more from me than was necessary (i.e. for papers), or that they realise I cannot achieve that and now are hoping for the best...!
I am really anxious about this and not sure who or what advice to trust! We have such a small group, and we are mostly PhD students so I cannot even get advice from post-docs etc.
So how much data is required for a thesis? Do you think 4 studies, one each chapter is enough?

It sounds like they are saying that in an ideal world they would have liked 5-6 studies. However you have been ill due to stress, so they have had to revise down from an ideal scenario. Four studies sounds ok to me, though 5 or 6 would be better.