There is a stigma about breeding animals too frequently, but in reality, there's an important balance to reach with brood rabbits. It's important to make sure the doe remains healthy while raising her litters, but going too long between litters increases risk to the doe and kits next time.
My general recommendation is to wean kits from the doe around 6-8 weeks old, give her about 2-4 weeks off, then rebreed her. Does should have at least two litters per year to stay in breeding condition, but 3-4 litters annually would be reasonable.
It's important to evaluate the doe's overall condition between litters. Make sure she is in good weight and flesh condition, eating and drinking a healthy amount, etc. Some does maintain condition really well and could be bred more frequently than others with little issue. Others may need extended time between litters to retain their body condition. It's very individual, so the general opinions you get are more of a guideline than a hard and fast rule.