Not always, there are thousands of people who put adsense on their site daily. There are also many people who remove adsense daily. In some of the niches I advertise, content match has worked very well (better than search), and the so called "traffic surges" convert just as well for me.
There were a lot of people home yesterday for Martin Luther King Jr Day, so that might have been the reason for monday.
I love holidays where "most" people just sit home, relax, and get on the internet.
I wish there was a "National Surf The Internet" day.