I have a very limited space which I am keeping my rats, they also have to be discreet as they are on an enclosed porch and we live in a condo type place. I breed for pet as well as feeders.
I may move females to be bred by different males for color/coat/conformation.
I may have too many babies in one bin, while another has a similar aged litter. Pinks can get pushed out by crawlers and fail to thrive if moms keep everyone in a communal nest instead of splitting into multiple nests in the bin.
Just last night I moved my 3 grow outs from the top bin to the middle so they wouldn't be as cold. They also haven't learned to make nests from newspaper, and one is a hairless. The adults in the middle bin will theoretically teach them to use newspaper and the grow outs can use the nest already made.
I just sold some unneeded adults to a fellow bp.net member and replaced adults with young holdbacks and had to do a little rearranging. Everyone got along and everyone fed babies that may or may not have been their own.
I also don't keep males that pester females too much. If they are causing a problem with the younger girls, they get put into my oldest and best breeder bin. Those girls whip him into shape.
I just expect everyone to get along, males and females alike. The head of the property committee that lives next door does not need to hear rats screaming if I need to move someone.
Most of the unwanted behaviors are easy to eliminate. After ensuring their needs are met, the behaviors are either learned or genetic. Removing the animals that exhibit the behaviors will keep them from adding to the gene pool and keep them from teaching the others to do the same unwanted behaviors.
My rats never even eat the bodies of dead babies anymore. My desert king snake is thankful of that!