We have 5 bedrooms, 3 baths, ONE kitchen. About 15 yrs (and 2 kids) ago we "popped" the top & added a master bedroonm & bath over the garage after checking out the local real estate. The size of house we needed was too expensive & those in our price range were smaller than what we had. So we added to ours.
But about 5 years before that we added a hot tub room. Fully enclosed, built-in hot tub. It was directly off the spare bedroom/office. Little did we know that spare bedroom would become a nursery!! Our kids were the only ones who had their own personnel hot tub! Talk about "child proofing"! You needed 12 keys, a crowbar, and a ladder to access the hot tub!!!
I don't know about the rest of you, but I have no need for 3 kitchens! I have enough problems finding things in my lone kitchen now. I'd never find anything if I had to look in 3!!!!