I would say that having one shower might cause more problems than it will solve. I have had and not had showers available in facilities. It didn’t seem to make any difference. But there was some competition for a single shower after group classes when I had only one. I like having a shower for myself to use so I wouldn’t stink after my own workouts. But it/they did/do require a fair amount of work keeping it/them clean for everyone using it/them. The cost of putting showers in was not too bad though.