I would be interested in knowing the Mothers childhood.
I was allowed a bath twice a week and similar for my hair, even though at times I could of done with washing it daily.
I went to school with a very clean year group and stood out because of my lack of hygiene. It was also a very Catholic area and on a Sunday all the little girls were dressed and hair done for Church. I played out with my hair au natural.
My Mother laughed off any suggestion that I needed to be cleaner. She wasn't house proud, either.
As soon as I left home it was at least daily baths.
None of my children had skin conditions and liked water play, so it was daily baths for them as well.
I think at 7, if a child wants to wash more than their parent does, then they should be allowed to, so it depends on what the DSDs want.
I know scruffy, or less hygienic people, who have no awareness of how they differ from others, or don't care, which is fine for an adult to decide, but children should have some autonomy around being clean.