Well, SD is nearly 7, but she showers nightly except weekends or days off from school and then we are more lax. She shampoos and conditions and washes with Aveno body wash. I think when she was under age 5 it might have been a bath every couple days (and hair washed). She sometimes forgets to wipe after peeing, so I think washing every day is important. There have been weekend days when she hasn't washed, and she happened to be in her underwear lounging on the sofa, and I caught a wiff of her privates and was grossed out.
I am trying to teach her the importance of being clean and dry "down there" because she's had chaffing/redness and itchiness in the past. Granted, I am probably not as informed about more "natural" ways in relation to bathing for kids or adults, but personally I like to bathe every day and think she should nearly every day too. Her maternal grandmother however doesn't make her shower daily (I think she just doesn't want to bother), and SD has said that Granny doesn't wash her hair because she doesn't want it wet when she goes to bed. That irritates me because it's not a big deal: either have her shower in the morning before the day's activities, or do what we do, braid her hair after the night-time shower.