I disagree with you completely.
The more questions you do the better you are prepared, look at this poll http://www.usmle-forums.com/usmle-st...-step-1-a.html
and you'll see people are saying more than 5000 questions are needed.
UW is good but Kaplan is also good. In fact many recent exam experiences have mentioned that Kaplan is closer to the exam than USMLE World, look at this man for example http://www.usmle-forums.com/usmle-st...-step-1-a.html