I could shower and soap everything quickly in a few minutes to, bit the GP comments were talking about taking 15 to 20 minutes to shower, which seems extremely long to me.

Nothing happens if I get soap elsewhere, I just don't intentionally soap outside those regions daily. In my experience arms, legs torso etc aren't particularly dirty on a daily basis and the skins seems more mostrurizied and healthy if I just use water on them. YMMV depending on skin type.