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).
The rate at which your hairs emerge from their follicles is constant, but the rate of increase of the total length of the hairs slows down and eventually stops because the hairs naturally wear down over time.
Imagine that your hair is like pasta being extruded into water, and that it slowly dissolves over time. The more time the pasta has been in the water, the faster it dissolves—and it eventually reaches an equilibrium length where the tip is dissolving as fast as the other end is being extruded. But if you cut off the pasta at the extruder and time the new pasta coming out, you’ll measure the full extrusion speed instead of the extrusion speed minus the length-dependent dissolution rate.