We use our towels for a week. I change them out for fresh ones every weekend.
Growing up my family used towels multiple times (I'm not sure how often my mom washed them), however my husband's family only uses their towels once. So when we moved in together and I started doing laundry I switched to only "one use" but the amount of laundry I was doing for 2 people was crazy - bc of all the towels.
I now have DH trained to use his towel for a week.

Now if my towel gets on the floor, etc. I will toss it in the laundry basket - but as long as it's just touching my clean body and the towel rack I think it's good for a week. I've got some weird issue about clean things touching the floor - I think it's the dog hair that I can't seem to keep up with no matter how I try, lol.