The thing you have to remember is that the UMAT aims to assess skills. Skills, unlike knowledge, are attained over longer periods of time.
So if you're struggling with section 2, for example, doing 150 drills of it in a row won't necessarily improve your marks. You have to find what it is that is making you perform poorly and aim to boost those skills in everyday life. You might read novels and/or other books to learn vocabulary and also learn to read faster. You might read psychology books and books about EQ to learn about human behaviour. For section 1 you might just read the newspaper and practice critical thinking there, weeding out the crap to get to the facts. You might get a problem solving or puzzle book, so even when you're not studying UMAT, you still are.
Don't think of UMAT as just another subject, where you study it for a specific time and when you're not studying it then you switch your brain off. You have to constantly stimulate your brain to build those skills necessary, that's why so many people "hardly study" and do well. Maybe they were studying, for the last 10 years through constantly stimulating their brain, and interacting with people.
At least this is what I've gathered from talking to people ^