Hey all,
I don't want to comment on posting the questions overall here, but let me just say this:
There is a ton of material out there. If you wanted, you could probably spend four full years studying for the GMAT and never have to do the same problem twice. Given the choice between doing 2,500 different GMAT problems and doing 500 GMAT problems five times each, I would recommend the latter option any day of the week. Doing a problem once, getting it right, and moving on means you did not even come close to learning all that you could from that problem...
You should be spending 8-10 minutes reviewing every problem you do. Before you can consider a problem or a concept "mastered," you should: Do the problem, check your answer, figure out why you got it right or wrong, identify weaknesses, determine guessing strategies, try to find ways to do that problem quicker, and overall just dive in and get 100 percent out of every problem you do. If you choose 20 problems and spend 10 minutes each (2 minutes doing the problem, 8 minutes reviewing), that's over 3 hours of study time. That's a good day's work...