Regular shampoo and conditioner are quite thick. So they pretty much stay in place in your hair where ever you put it. They’re also pretty easy to even out without losing much.
But apple cider vinegar is a pretty thin liquid, almost like water. So it’s easy for it to just go straight down the drain after pouring on your head.

What’s a good method of dispensing ACV through out your hair evenly, without losing too much of it straight down the drain?
I’ve also had the same issue when pre-mixing baking-soda with water.
I soak about a minute then slowly pour the mixture over my head to make sure it covers my whole head. I’ve heard other say the mixture should not go on the scalp but I pour it right on my scalp - it helps to condition both hair and scalp. I also use the cheap store Heinz gallon ACV instead of the organic stuff with “mother” as that stuff left all kinds of nastiness in my hair.