Depends on my schedule and who's paying for the water usage.
These days I have a very early shift so I try to get up as late as possible, allowing myself enough time to have coffee while checking email. I wash my hair in the evenings now so it's dry before bed so I do a quickie shower in the morning, maybe 5 minutes.
When I'm working a later shift, starting work at 8 am or later, I probably spend a good 15 or more minutes in the shower. Like BG, I tend to plan my day best in sauna-like conditions.
Days off are different. If I'm running out in the morning, an in-between shower is in order. I know I have a lot to accomplish so can't really chill. However, if I have a "date" or am going somewhere for the evening, give me a good 20 minutes.
