Everyday. You can put the baking soda on dry or mix it into a paste. Make sure you massage it into your scalp (not too hard). Then you rinse that out and put on a rinse of vinegar water. I comb my hair out at this point and then rinse out the vinegar then apply a little vitamin E oil after I towel dry it.
I stopped using shampoo years ago because I’m allergic to a lot of the stuff that goes in them. I use baking soda and apple cider vinegar (you rinse in between so you don’t make a volcano). My hair has always been brittle and frizzy, but now the texture is really nice.
And for the record, no my hair doesn’t stink. You can use vitamin E oil after with essential oils if you really want your hair to smell pretty.
Maybe I’ll stop getting those “He Gets Us” ads if I cruise the atheist subreddits.