Shrimp population density

This might be a "everyone-has-their-own-opinion" type question, but generally what's the rule about how many shrimp you can have per gallon without overcrowding? I know that it also depends on the water quality and maintenance schedule and whatnot, but assuming that as the population increases maintenance increases as well to maintain the necessary water quality is there a "magic number"? Thanks!

I have a combination of cherries and crystal reds in a small planted 5 gallon. I have 5 crystal reds and am picking up 7 more tomorrow plus two babies that I spotted yesterday. The cherries I started with about 10 and now have probably about 25. I figure I'll probably have to start thinning out the cherry population soon, especially as I want to have more space for more baby crystal reds but I wanted to see what generally is a good number to shoot for in such a little tank. Thanks!

Hahahaha... First, I'd like to mention that I find it amusing (and fantastic) that despite me not having a list of them in a signature or anything, you assume (correctly) that I have other tanks like it's the most natural thing in the world to have several tanks in one household. As my husband points out, this is why I love this forum - I feel at home...

Back to the question at hand - I only have one other freshwater tank and it's a community tank with dwarf gouramis and small loaches - any shrimp that I put in there would be snapped up as a tasty treat in a second. However I do aim to start thinning my cherry population sometime soon to help increase the crs population. Thanks for the advice - I had heard that before and have been keeping an eye on them at feeding time. I've actually found the crs to be quite the bullies during feeding time, often fighting off the cherries from the wafers until they've had their fill... Regardless, what numbers should I be looking for before I start thinning to maintain a healthy population as far as total shrimp go or a crs to rcs ratio? Any ideas? Thanks!