I normally take mine in the mornings before school, so that means I have to take short ones since, well, firstly I don't have the physical time to lounge about afterwards and I have to make sure my hair is somewhat dry by the time I leave the house. Secondly, I have to save some hot water for the rest of the family if they decide to take a morning shower too. <_< So yeah, generally those showers last 5-10 minutes.
If no one needs to shower after me and I've nothing to do, I could go well over 35 minutes. =D