We all know what tweaking the google Adsense is: change ad color, placement, ad group count, etc and hope for an improvement in revenue.
Tweakins is attractive because it's easy to do (how's that compared to writing content?

ops: ) and to measure with the canned Google stats.
The question is: what are typical improvements one should expect from tweaking? And when do you stop tweaking and worry more about improving your copy and fundamental numbers?
I have seen claims as high as 10 - 15 X. I think that's highly non-typical for most adsense publishers. My guess would be something in the region of 2- 3 X increase in revenue.
What's your opinion on typical revenue gains from tweaking Adsense?