As a bald guy, my showers are pretty darn fast. Abrasive scrub with my fancy soap all over within 5 minutes on the usual, add 5 minutes about once or twice a week for shaving. When I shower with someone else they usually have a lot more involved with their shower and I'm out before they really get started.
I mean, I'm definitely not opposed to showering with a significant other, but I usually let them know that it's not going to be what they think it will be lol
Entirely about intent! I HAVE dated someone that just wanted some us time even if not physical, then I'd hop out and dry off but hang around while they did the rest of their shower