My limit is based more on what my back and knees will take, assuming there are enough targets to dig. Even without bending or kneeling to dig targets, after 5 hours max just swinging the coil I'm ready to call it quits. I routinely have 50-coin days. I commonly have 100-coin days, and my "highest coin count" so far is 153 coins. That might sound impressive to some, but consider that 114 of those were memorial cents and my total face-value take was $8.14 including one 1943d Mecury dime. This was at a school complex, where the elementary, middle and high schools are all situated in about a 2-block area.
My personal strategy is to mix up the types of detecting I do. I'll hit one area knowing it's more likely to give up silver (but far fewer coins total) for a while, then I'll spend a day hitting a school or park where I can find more stuff but not as old. Then I'll hit someplace really old where I expect to find very few keepers but the chance of one of them being really old or valuable is higher. This routine keeps me interested and isn't as boring as either never finding much at all or finding a lot that isn't very valuable. I do have to admit to being addicted to finding silver coins, though, and it took a few weeks for me to lock onto my first one.
I'm sure some people inflate their finds in either numbers or value, and I don't care. The only thing I really get out of these posts is ideas on different places to look and techniques for searching or recovery, I couldn't care less if some lucky detectorist finds a gold bar or a bag of silver coins. I'm not wherever they are and probably never will be, so good for them and "whatever" for me. I'm in competition with myself ..... and HEY LOOK, I'm WINNING.