if you have lots of plant and décor hiding places for the shrimp babies. Java moss and other fine leaved plants are very helpful, such as hornwort, riccia, subwassertang, any mosses really. I also use some cholla wood which seems to help. It is dried out wood from a certain cactus that has lots of holes in it. It creates a tube for the shrimp to hide and forage in, also provides a minI cave for protection when the shrimp have molted.
I keep corys, otos and assassin snails in with my RCS. I tried keeping endlers in there, but they slurped the RCS up like spaghetti. No more fish after that. It took me a long time to get my RCS population back.