Karate lessons can be expensive and not everybody can afford them so I was thinking, just how common is it for a sensei to hire a student to do work around the dojo and instead of paying him with money he pays him with lessons? Sort of like how Miguel Diaz was working for Johnny Lawrence to fix up the dojo when he first opened it up, before Kreese took it over. Or it could be argued, how Daniel was doing all that work for Miyagi, waxing cars, sanding decks, painting fences, ect.