That's the pattern I'm seeing as well. A few clicks in the morning, then zilch for the rest of the day. Usually more clicks come in in the evening, but not always. Sometimes, the early clicks I get is all there is for the day. Overall, May has been a very weird AdSense month. Oddly enough it's somehow already beat April, so at least on that front I'm happier. Hopefully they'll stop turning the knobs so much come June!