[Symbiote]

I think that's it.

I have a very wealthy relative who lives in the USA, and I visited when my younger brother was just 6 years old. It took him several complete tries of running round the house to count all the bathrooms (and not lose count).

There was one per bedroom, then one on the ground floor, one by the garage and one which was easy to get to from the beach.

The neighbour's house's guest room's bathroom was also the general bathroom; it had two doors with appropriate locks. This seemed like an efficient design.

[frosted-flakes]

Bathrooms with two doors are annoying. Typically, the door to the bedroom gets locked and not unlocked, so you have to go around to the hall door anyway. Also, unless the bathroom is large, the doors typically clash.