I go 2-3 days all the time. I used to wash every day when I was younger, but by 27-28 years old, I found that I was really breaking my hair down by doing this. I also have highlights, so I want to try to minimize the damage. If I work out, obviously, I wash, but if not, I can easily stretch it several days. I actually read in Allure, I think it was, just recently(they had hair models they were interviewing) where the girls there with perfect hair were saying once a week. One of them even said she had waited 2 weeks so that the natural oils would get all the way to the ends. ICK. I could not stand myself if I waited that long. It would be horrible. I think a lot depends on the hair texture, the amount of hair you have and the tendency you have towards an oily scalp. I noticed that as I have aged a bit, my hair is much less oily. I also will wash more in the summer as the sweat factor makes it more necessary more often. All in all, I used to hate going more than a day, but now, the longer I can wait, the better I feel about the damage I do to my hair.