Anecdotally, my office has about 60 employees and 8 individual bathrooms. They're fully enclosed with sinks and their own heavy closing doors. They also are all equipped with a white noise machine that's connected to the ceiling light switch. I guess we're pretty lucky to have this setup.

About two years ago, however, someone complained that all of the bathrooms were becoming "too dirty" in between weekly cleanings and it was blamed on the men. Therefore, three of the restrooms are now women only, while the remainder are unisex. It seems a bit unfair, but nobody has cared enough to complain.