Part of the whole congestion issue in Y is due to some people going to the loo much more often than what they'd do at home. It could be boredom, I suppose, as you get a chance to sit and think about ablutions and suchlike.
I've seen it plenty of times. 90 mins flight time, several people using the toilet 3 times, sometimes more. These were adults in their 20's and 30's. I obviously don't know whether all these people have bladder problems, but I do think it's boredom.
Now, if it wasn't for "everyone" going to the loo as soon as the meal service is done (LH), there wouldn't be so much congestion either. Yes, go when you need to, but just be quick in there when there's a queue.
I'm one of the "evil"
ones that send the passenger back to Y unless there's someone with a mobility problem or medical issue. Hate me if you like, I don't mind, but my Club passengers usually thank me for it.