I’ve often been told that this isn’t actually true but I can’t help but feel that it does happen. Until recently I hadn’t shaved for about a year, maybe two. Now I feel like it’s growing back quicker than what it did the last time (after shaving on a more regular basis).
AFAIK, apart from drugs, only stress and malnutrition affects hair growth speed. Stress can increase cortisol levels, which can lead to faster hair growth, but chronic stress and malnutrition may lead to hair loss.