I have extremely thick hair, but only use shampoo once every few weeks because too much absolutely ruins my hair texture. Nonetheless, just rinsing my hair thoroughly with warm water and then cold water takes at least 5-6 minutes per shower.

I think the greater point is that hair maintenance varies greatly from person to person, and it is absurd to assume every male only needs 2 minutes or every female needs > 15 minutes. A great example of the stupidity of stereotype and how it leads us away from useful thought.