I am applying to six universities. I think it's just a matter of how many institutions you're actually interested in pursuing and how much time you want to spend applying. As far as the GRE, the writing is the worst part for me. I retook it this fall and got a 4.0 again. My verbal is high and my quant is pretty good, but I think the GRE is usually considered as just one of multiple factors (and is perhaps not a super important one?) institutions look at in determining whether or not they want to offer admission. Best of luck on all your applications!