The thing to be careful of if spreading out exams is you only get a maximum of 6 sittings and if you mess up an exam on the 6th you will have to take them all again. I have just started with CATS and so far found them very helpful. Plus it is only 3 weeks gs which suits me better. there is some flexibility around number of sittings but I think it is a safer and possibly cheaper in the long run to aim at 3.
Godd luck with your choice.