How many times a day can i wash my german shepherds ear?

I have poored a 2thirds water 1 third vinigure in my dogs ear and messaged it in it looks like im going to have to do it a few more tymes to get that blackish brown stuff out she shakes her head very hard after i do it which in a way is good cause thats the only way to get it out but i dont want her to hurt her self shaking her head anyway just wanted to know in this situation how many times a day i should do it