If I don’t wash my hair (just tie it up and out of the way) I can get myself soaped and rinsed in about two minutes.
If I also use facial scrub that’s another minute right there.
I rarely spend more than ten minutes in the shower, because…dorm showers. Yuck.
I can get my business done in 6 or 7 minutes. Wet hair, lather, run soap all over the bod from top to bottom, rinse.
That depends. I use Pantene 2 in 1, and it works excellently on my hair. I have curly hair, though, and by curly hair products.
In answer to the OP, I can cut it down to 3 minutes and get everything shiny clean, if I have to. Including my loooong hair. My average shower is usually 5-10 minutes anyway. If you’re in there longer alone, you’re either sleeping or masturbating.
In *my * humble opinion. 
…not that there’s anything wrong with that
I enjoy having an ‘assistant’ in the shower with me to help things along, however when I tried this with a female companion I took far longer to finish cleaning myself than normal. Hmm
I didn’t say there was, I’m just saying masturbating & sleeping in the shower…don’t necesarily do the same thing for different people.
And I have to confess that I don’t really like having anyone in the shower with me. I’m not saying the boyfriend and I don’t ever double up, but I just don’t like it and probably won’t like until I get a ten-foot square tub. 
<ob>Wanna see me do it again?</ob>
If those are my only options I guess I’m sleeping, because I’m sure not doing the other. Not standing up and all.
I went to a small summer camp every year growing up. Two showers for ten kids, and some of those kids apparently didn’t understand how hot water heaters work, and took loooooong showers. When I was thirteen, I became a counselor, and counselors shower last. So I perfected getting clean before the hot water ran out. Shampoo, soap, rinse, done. Maybe three minutes tops.
I take slightly longer showers the rest of the year, but my camp habits are ingrained pretty deep. When I was living in the dorms, my suitemates marveled at how little time I spent in the shower. I can’t shave in an actual shower, due to an inability to see what’s in front of my face without glasses. I guess that’s a contributing factor to my speed.
It’s my shower, and my tadger, and I’ll wash it as fast as I want! 
Barring any of that, if I’m going for speed I can get it done in about 1.5 - 2 minutes. Get wet, get soapy, rinse off, get out.