I think you're going to find that the time required varies greatly.
For Part I... I barely studied. (I brushed up on EJB3, since I don't use it very often.) I perhaps set aside five hours for that section, but you may find that you need more.
Part II was different for me, since I took it during the Beta. We had an artificial deadline of about a month to accomplish it, but even then, I really did that part in about a week and a half, with the last week of it being fully dedicated to working on SCEA (so let's say about 60 hours, all told).
Part III took no preparation, since doing the Part II assignment was the preparation.
The time required for the Part I/III exams should be posted on the Sun website, if you're adding that in as well.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!
I think that's a testament to your knowledge. I think most people would have to put alot of time into studying for part I. It really covers a huge amount of information, and you really need a well rounded knowledge of JEE development to pass it.
I actually wrote Part I cold, but it was the Beta, and I was doing it more for the joy than anything else. But I think this would take a significant amount of study time, as the objectives are wide and broad.
For Part II, they say 40-60 hours. I thought "yeah, but I've got a real big brain. I'll do it in 10 hours." Well, my brain isn't as big as I thought it was, because I probably spent over 80 hours, as I did it, changed it, decided I didn't like it and did it again. It's a very tough second part.
Part III almost doesn't require study if you really understand what you did in Part II. Part III really asks you questions about why you did certain things a certain way in Part II. If you really did Part II, and understood what you did, Part III would only require a review of your project and design decisions.