I'm not a big fan of tags, because you loose the ability to control your onsite linkjuice!
And yes - if you do decide to use tags, then why would you like to overdo it. You are only going to focus on 1 or 2 kw for each page anyway!
I use sometimes 100 tags. They are really important. Forget the ones underestimating the power of tags and limiting its number to 2-10. I assure you that 20-30 is pure OK.
do you mean each page or each post? is it better to use pages?...i have just been using posts.