How often do you wash your kids hair?

[NoCapes]

I don't mean to start one of those threads, just genuinely questioning how to do things

My older DC have a bath or shower on a Sunday, Tuesday and Thursday nights and on a Saturday morning and I generally wash their hair every time
DS's is pretty short so not an issue but DD's is getting quite long now (she won't have it cut any more than a trim) and she hates having it dried, so it's becoming an issue and this week I haven't bothered having a fight with her about it and left it

She's only 5 so it doesn't get greasy or smell
She hasn't had it washed since Tuesday and it genuinely looks no different than it did before

Would it be really gross to tie her hair up in the bath and only wash it once a week on a Sunday?

DD1 - once a week. She's 5 with mega thick hair. Never looks or smells unclean.

DD2 - a few times a week. She's 2 and a mucky pup, so we wash it whenever it's got food or general mank in it!

I bath my 5 year olds daily and their hair is washed once a week.

Every other day,more if sweaty

Twice a week

Bath every night and hair wash twice a week.