Hi Mtek,
I have them on all the pages of my site but they were set up for me and to be honest I only make a few dollars per month from them. I don't know if there is any sort of tweeking I can do so maybe I can do better with them but a lot of people don't have them at all.
In fact I am thinking of taking them off and using the space for something else. Give them a try by all means, I only have adsense for content which is the ads but you can also put adsense for search which is a search box you place on your site which you get paid on that as well but don't know how much, I guess like most things you can suck it and see and it's free so why not. I hope you have more success than me if you try it out.
regards,
Mal.
Work at Home Ideas and Opportunities