Let's see, it takes about a full three weeks of hard pounding and seven or eight passes over the manuscript before I'm satisfied. I tackle one element for each pass instead of trying to do a complete edit, tackling all aspects. I used to do three passes (revisions) but found out that it wasn't enough, since my agent was throwing it right back at me. I revise word choice, plot holes, grammar, passive, format, sentence structure, characterization, and other elements all seperately, so I can concentrate on each before I make the next pass. I have a terrible comma problem, too, that needs its own pass.
This only works for me since I'm so rotten at revising my own work.
Tri