Daily Quiz is an extremely helpful and convenient way to keep your quant skills daily. Most important thing about studying GMAT is that you should not cram. Not just for quant, you need to study all areas everyday to make sure you have those senses. of course, most of us are working so I would hardly have the time to solve 31 questions in one day. It would be actually really tiring too because I have verbal to solve. In such, I would make use of Daily Quiz. 5 questions, but I could use all the skills I learned through variable approach. Plus you receive the questions through email so you could always get access to your questions, whether you are at work, home, bus, metro, anywhere!