I agree - often the last few days of the month are great. The dip always occurs for me at the start of the month. Not going to try and explain it.
For me it's roughly the same. The first half of the month I often feel a bit disappointed by the amount I make, and it is usually compensated by what happens in the second half.
Hmm, funny, I usually get poor traffic and clicks at the end of the month. It must be due to a certain niche area we are workign in.
That's really funny, I haven't noticed anything like that. Maybe people at the begging of each month are to buzzy spending their money.
In theory, at lesat, a drop should occur toward the end of amonth on the assumption that advertisers run out of their budgets after running a fearless campaign, however, to me, and I am sure many others, find the best and worst period of the month is often very unpredictable.
qwestcomm's theory makes sense, but you also have to figure in the area you are targeting, for example proxies sites tend to see more traffic and therefore more revenue during the weekday then they do on the weekend.
It's interesting but for the last few years, my traffic always drops immediately at the beginning of each month and builds to a maximum at month-end. Of course, my earnings follow the same pattern. I have no explanation for this behavior.