I studied for a week for about 12 hours per day, the week before that a little less and the week before that even less. I had taken two years of graduate courses already (algebra, homological algebra, algebraic geometry, real and complex analysis, differential geometry, algebraic topology), so I knew the theory really well and only needed to brush up on calculating integrals and solving differential equations.
I also spent some time going through old tests and thinking on each problem if there was some standard example of a mathematical structure that could be immediately used to eliminate some answer choices. I then wrote all of them down and remembered them. It turned out that a pretty small set of examples were the only ones needed to solve practically all the problems on all the practice tests which asked if some equation is always correct.
My score was 97% BTW.