For me, I want clicks, but I want visitors to hang around as well. So I never have added the "recommended" amount of as. I use 2 per page. One above the fold, and one at the bottom. I enable text/image and that's it. Seems to do well...for me (my sites). You need to figure out what does well for you (your sites). Make changes to one of your high traffic pages, and wait 2-3 weeks. No improvement, make more changes, then wait again. Once satisfied, change others.