My girls are still young but we are in the planning phase for their coop. I have 2 Rhode Island Reds and 2 Silkies, do they each need their own nesting box? Is it more important to have a larger hen house or a larger run?
If I were you I would just put in 2-3 nest boxes. We have three hens laying who share two nests.
My coop mainly just supplies a place to sleep at night, a place to lay, and shelter if they need it, so really I don't have all that big of a coop. Just go by your estimate and give them something they'll be comfy in.
They do not need their own nesting box. Chickens often choose the same box to lay in so one will be empty and one will have a huge pile of eggs but I would create a minimum of 2 so they have options and can lay at the same time if they need to. Also try to amke it darker than the rest of the coop so they can be more comfortable when laying.
They need about 10 square feet per chicken in the run and 4 square feet in the coop.