Wow, I rarely bother to clean my stylus (perhaps once every 8 sides or so) and I have been using line contact styli for a long time. I suppose it is possible that the stylus is digging up long-deposited crap in the grooves (I hope it is not chewing up vinyl and depositing that on your stylus), but, your experience seems extreme. if you don't stop and clean the stylus, what happens? Does it start to mistrack? It is unclear how extreme the build up is such that it prompts you to stop play.
My records have been cleaned using a Nitty Gritty machine. More recently, some have been cleaned using the Audio Desk ultrasonic cleaning machine. It would help to know something about your record cleaning practice.

