If living in cages, then no it's not too big. I thought you were talking about nest boxes in a normal smallholder system. The more space the better.
Caged systems are unnatural so you have much different considerations.
Caged birds have advantages and disadvantages. They usually don't contract things like coccidiosis since they're on wire. If there's more than one bird in a cage, you'll probably have to debeak them. They can't do their normal behavior like dust bathing or finding a dark quiet place to lay eggs. Laying eggs in light where everyone is watching is unnatural.
You may be better off finding information related to commercial systems than backyard flocks.
California has a new rule for space for egg layers. I suggest you use those dimensions and requirements. While it's still unnatural and too small, it's better than how they have been raised.
and Welcome To BYC! You might want to check out the Feeding/Watering your flock for watering systems 
