I feel weird showering everyday. That being said I shower every other day (unless I'm really dirty or feel that way), but max is 4 days. I feel gross on the 3rd day though.
If I don't shower at night I feel sticky because I exercise every day, so I can only go one day without showering, and only if there's a valid reason I can't take a shower (i.e. it's 2 or 3 am and I just want to go to bed).