I agree with the bathroom for every bedroom, in fact it should be +1. Same goes for garages, One garage for every bedroom +1. A 3 br house should have 4 baths and a 4 car garage. I looked for that house but couldn’t find it, had to get a 5 br with formal living and dining rooms of which I didn’t need.
I know a guy with a wife and three daughters who owns a 4br/1ba, 1 car garage that was built fifty years ago. He’s in “man hell” and he pees in the backyard every day (actually that’s the only benefit).
The bathroom/garage ratio is a lifestyle thing, albeit one that probably wont last forever in my case. I have a teenage boy and girl. The three of us get ready for bed and work/school about the same time each day, we are also approaching the time where we will each have a car, plus i have a work car. We only need three bedrooms, one livingroom and one dining area, but we could each use a shower and a garage space, plus a bathroom for guests and a garage space for a workshop. I don’t want guests to be subjected to a teenager’s bathroom and i refuse to clean it. They shared a tiny bathroom for a few years while we rented, it had no counter space, one little cupboard, no drawers and the toilet and shower was in the same little room with the sink. May daughter eventually took over the second sink in my bathroom because there was no place for a curling iron on her “counterless” sink. Pedestal style sinks and minimalist ones look cool but are a pain. Girls have stuff, even those that wear very littl make-up have curling irons and hair dryers and other chick stuff. They could share a bathroom if it was the two room kind, where the toilet and shower are separated by a door from the sink area. It’s hard to find that in secondary baths. Now they each have a two room bathroom to themselves and they each have two sinks of their own and it is fantastic compared to the sharing days.
I also have two cars and a workshop, so the three car garage is all mine, kid cars have to park on the street.
I had to get a mcmansion to find what I wanted with regards to bathrooms and garages, but I could have gotten what I wanted in a home under 2000 sq feet if i could design it myself. I have no use for the three livingrooms and two dining rooms, one of each is fine, but in order to get the bathrooms and garages, you get stuck with the other stuff, just the way it is.