I've done it few times as a prelude, you need the right shower though, a tiny shower or an over the bath type aren't the best, once a Brazilian suggested we share a post punt shower, I'm in my late 50s and it's unlikely I can pop again so soon after the main event but I was happy to have a play around and see what happened, unfortunately there was no hot water so it never happened. Given that this was in time after my paid time was over I don't see that happening very often and I wouldn't want to pay for what would be an effectively fruitless extra 15 minutes.