Agree with everything said, though I must say that sometimes I get poor results from an advertising site one month, only to have decent results the next.

I discovered this accidentally through laziness after just repeating my previous months advertising without first checking my stats.

When I did check, I noticed that some sites were good one month, not so the next.

Now I give each new source at least 2/3 months to get a real feel for how they perform.

So while I agree that some form of tracking is essential, it’s not fool proof, especially in the short term.

But of course persisting with proven poor performing advertising sites is simply a waste of time/money.