It seems pretty selfish to deny female rats a break, just because we want to pump more babies out of them. Again, this is my opinion. To each their own.
I do have some dry spells, but I am growing up 0.6 right now to supplement this operation.
I don't see how you can call it selfish? Rats in the wild don't get breaks. My rats are fed top quality food and live a normal lifespan for a rat. Probably even a bit longer than normal when compared to wild rats.