I vary so much. I freaking love showers, and I like them hot. Ideally I would like to sit in there for half an hour or so, as for some reason I do a lot of deep thinking while showering.
Alas, constraints usually make that impossible. Since I shower in the morning and need to get going, and want to be courteous to my housemates, plus financial reasons, I usually only take 5-10 minutes. I do shave in the shower, though, so every few days I'll add a few minutes for that.
And every once in a while, usually on a weekend when I don't work, when I have nothing going on and I just feel like relaxing, I'll treat myself and take my half hour luxury shower, and it is glorious.
As an aside, would anyone get a Seinfeld Kramer reference if I were to make one?