Thanks to the person who posted about their aunt's study, interesting.
okay, let's remove children from the equation (I'm never really at places where children are a factor in slowing the queue and see this all the time).
think of venues like over 18s festivals, pubs, bars, nightclubs etc - usually need to think of situations like a queue for the loo at one particular time because people don't want to pee at midnight on NYE or it's the break between whoever is on stage. Or even big seminars at conferences etc.
again, no kids.
bearing in mind there will be men with health issues, women with health issues, which queue is 3 times as long as the other?
I was at a theatre with literally no kids in the queue for loo. (Thinking about it, there were probably more men at this show than women). My companion has a prostate issue and went before the show, after the show and twice during the interval. I went after the show and honestly I felt bad how long he was hanging around waiting. I hardly had to wait for him at all, I had time to take a couple of sips of drink. When I went, I could see how fast the gents' queue was moving. (I asked my friend and he said there were urinals and some cubicles, so I didn't use the gents because I think it's unfair to them to barge past them at the urinals).
I wonder if there is a behavioural issue - some women think it takes ages to get through the queue, and then are very slow themselves because they just think, oh well, it takes ages?
I had forgotten about Spanx I admit. I also remember, as a teen, my mum said to me "how can you be so quick in the loo?" - She wears a sari, and I said well, of course you take ages faffing with that. She was very defensive and said "no I don't, I've been wearing saris all my life, that doesn't take extra time". But I beg to differ. So some people who are wearing Spanx and goodness knows what else may take longer.
I don't even wear skirts so I don't have to make sure that they aren't stuck in my pants or whatever.