When I did q-banks, like when I completed Rx over winter break, it wasn't really about focusing on learning everything about every question. I gunned through it to basically evaluate how badly I had been screwed over by my school, and then made plans to be sure that I had covered everything by July. Plus it was a good intro to just see the format of the test, the types of questions, like a warm up if you will.
Later on when I was doing Kaplan starting in March I went through their books and then did their bank and tried to build on my mastery of topics. Despite buying World in December with the goal of doing 46 questions daily, I never really found the time to make a dent in that until mid-April once my school used my score on Kaplan's exam to sign off on my eligibility with the ECFMG. I regret not doing more of U World consistently but what can you do. I just had too much going on with school work piled on plus the standard 20 something roommate drama.
These last two months will have me finishing off GT in the next few days, then hitting U world / FA / Goljan with a vengeance, keeping on with the gunner q's.
During this whole time, every night I did gunner and tried to bank more and more until I fell asleep. But by far for better or worse the vast bulk of my time to date has been on Gunner. I have a less technologically inclined friend who did a similar approach with going through first aid, he's gone through two copies so far, and I guess we'll see how we stack up when our scores come in.
In retrospect Rx and Kaplan were a total waste of money, especially considering I had a concurrent Uworld subscription, but I wasn't going to take any chances on missing out on a good resource. And then there's the fact my school made me take the Kaplan stuff, so I didn't want to pay for it and not use it. Learn from my mistakes!
I just realized I didn't answer your question properly. Initially I tried to do stuff by subject, but lately I just hit unused / random so I don't get overconfident about my %. Most of the people I respect who are good students tend to do the study heme-> only heme questions pattern though. Either way I plan to do UWorld 3-4 times to the extent where it won't matter how I tackle it.