but you just have to hope there's no selfish people who think nothing of locking themselves in there for extended periods while there's a queue of cross legged people waiting outside.
Not only that, but the selfish people will take their phones in with them and engineer it so that their spouses/partners jump in straight after them.
It would actually be better if the room with a bath in it didn't have a bath at all and just a toilet. Some people will deliberately not use it out of consideration for others waiting, but there are always a few who will say "Well, they wouldn't have put a bath in there if you weren't meant to use it!" and then luxuriate for hours.
I'm amazed that the owner hasn't realised the situation and considered adapting the property, if possible. Depending on the layout, they'd be attractive to far more potential customers (and could charge more for it) if they had, say, 7 bedrooms and 5 shower rooms.
En-suites are great for reducing numbers using the communal bathrooms when you have, say, 8 guests (4 doubles) and two have en-suites, thus taking half of the guests out of using the main bathrooms; but 4 out of 20 is nothing.
Those lucky enough to get the en-suites will probably find that it's a poisoned chalice, as the others will be hating them whilst simultaneously expecting to be able to continually traipse in and use them at will as well as the communal ones. At least if you get a room without an en-suite, you'll have your own privacy.