I studied 255 hours and got 630
Basically, I studied to much Calculus and almost nothing of Abstract Algebra, Analysis and Topology. I did that because I an an Engineer and was not familiar with those subject. My view now is that no matter how sharp you are in Calculus, you will not have the time to solve all Calculus questions (considering you are not a 99 percentile freak). Consider two very hard questions of Algebra and Calculus, if you are very sharp in both subjects, you will take around 30s in the first and maybe 1m30s at least in the second, as Calculus involves more calculation
So my approach now is to balance my study between all subjects and see where it takes me. I will be taking both Sep-17 and Oct-29 exams. I wish to score 800 at least.
You can find details of how I studied in my blog