I've seen this topic on the boards before, but thought I'd bring it up again....
In my 20's, 30's, & 40's, I would never skip a day of washing my hair. Just the thought of it made me cringe. However, these days (in my 50's), I'm able to go several days without washing. Thanks goodness for dry shampoo! If I had a wash-and-go hairstyle, I'd probably never skip a day.
Back then, my skin and scalp was oilier than present day. So, I'm sure that has a lot to do with it. I prefer my hair when it's newly washed and blow-dried, but I just don't do it everyday anymore.