My husband and I have been on team shower-only-when-you-need-it for a year or so. We're both desk jockeys and not especially oily people, so we really don't need regular showers. I think the standing rule is, "Once a week, whether you need it or not!" ;). Seriously, anything that both indulges my laziness AND saves money / resources is right in my sweet spot.
Interestingly, in the winter, it really seems to help with my husband's dry skin and eczema. I've also moved away from shampooing my hair -- just a nickel's worth of conditioner when I shower. It was a bit of an adjustment, but now my hair is super healthy and soft, no need for product ever. I'm on the lookout for a good DIY hair conditioner recipe if anyone can recommend one!
Another interesting thing--stress sweat really does smell worse than regular sweat! If I'm sweating because I'm sweating, I don't notice it. If I'm sweating because I'm stressed, I can smell it immediately.