Simply question, how often do you change the placement of ads ? I think that is useful, because if ads are always on the same place that isn't interesting, nothing new and less and less clicks on ads. Your opinions ?
When they stop working. I have recently changed them on one of my sites and the change has been amazing! I have increased my CTR about 5 times!
yes, a perfect time to change the ads place is when the click rate goes down. this sometimes give a pretty good results
Sometimes too many changes are unneccessary, you just have to try and drive traffic which will bring clicks.