The great thing about this industry today is that there are many choices. And that line about things working different for everyone is 100% TRUE. What converts @ 1:100 for one webmaster might convert @ 1:10000 for another... there are so many different variables - the season, your content/site/gallery, the banners you choose, your traffic, the niche you are targeting, etc. etc... it goes on and on...
Same thing with choosing a limit - or a cut off point for dropping a sponsor. The cool thing is that you don't have to drop them completely - they just might not be converting well for you on one niche, or one type or program - again, there are many variables.
The best advice is what I was given years ago by many of the smart veterans on this board... try a little bit of everything, experiment, get messy - make mistakes, learn from them and keep going until you find what works for you.
Don't throw away the sponsor completely - just try other sponsors as well to increase your potential for $$$ and try the old sponsor in a new way.
