Big Carp News has an interesting article about the pro's and con's of long vs. short fishing sessions. Most of the time I can only allocate a certain number of hours to fish on any given weekend. I try to arrive early before sunrise and start fishing. Then I try to stay for as long as I can; usually around 4 p.m.
In Southeast Michigan I am not aware of more than one place that allows overnight camping. I know of another place that does allow overnight fishing, but it has the potential to be a little "sketchy" late at night. It's in a somewhat industrial area. Still, I might try it sometime if I can find a couple of other guys who want to fish an all day and overnight session at that venue.
I am sure longer sessions are better than short sessions and I have seen fishing be slow all day long and then pick up unexpectedly in late afternoon. Leaving even 30 minutes earlier can sometimes mean the difference from catching a couple of fish vs. catching 5 or 6 fish.