I'd recommend really learning an effective strategy that I acquired about two weeks prior to my Further Mathematics exams. A week before, all the practice exams I completed, I completed with (a) no reading time (b) not checking over the exam and (c) correcting it immediately once I had finished. Initially, I intended to do this purely because I had very little time and wanted to study for Biology, or perhaps complete other Further Maths exams, etc. However, I found this so effective because I found exam 1 rather tricky, and time-consuming questions got the better of me. I was not able to check over my paper once; not even once. But because I had the mentality that I have one shot to get this question right, I got most of the paper correct.
Also, don't assume that doing hundreds of practice exams correlates to getting a 50. I know friends who did nearly 100 practice exams in total, were scoring close to 100% on each paper, and ended up with scores they were disappointed with. Its all about learning strategies. Your mantra when doing practice exams, is strategies.
Best of luck