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).
As a transgender woman, I have personally experienced that hormone replacement therapy (HRT) – which includes estrogen as well as testosterone blockers – slowed down my facial hair growth and thinned out of my facial hair. So testosterone levels play a small part in facial hair growth. However, I doubt that the levels within a cisgender male would vary enough to cause any significant changes.
It’s probably just that there’s a fair bit of hair growth that happens before the hairs reach the surface of your skin, like a millimeter or two. When you shave, it only has to grow back enough to pop out over the surface of the skin. If you were to pluck a hair with a pair of tweezers, it would take at least a couple of weeks to grow back. I have done exactly that many times, so at least for me that’s the time frame.