How many times a hair must be pulled so that the follicle become damaged. After 3-4 times of pulling the hair can grow back?
I don’t know the answer to your question, but I suspect it varies with the individual. Patients with trichotillomania pull hairs over long periods of time. Those people who pluck their eyebrows may be able to give us an answer.
I have plucked my eyebrows between my eyes twice a month for over 10 years and it still grows out like crazy.