I thought I would try an experiment with my two tail biters. I just moved the more active biter to a different location with more items in the tank to distract him. I also started feeding him twice a day.
He continuously bites his tail and the tail has never grown beyond what you see in the photo. I have tried all the medicines I can find for tail rot besides the clean bowl and salt methods.
This fish is much more agressive than the smaller betta. He's also a bit older. He bites his tail when experiencing something new from his normal routine. Change something in his tank and you'll get a bloody tail as a reward. A new fish causes a problem. However, not a fish that's been in a close position for several weeks.