As a guy who learned to fell trees professionally under the same mentor for ~4 years, all I can say is that I've never seen a homeowner who actually knows why what happens happens, or how to use that knowledge. The only way to gain more than a very sketchy, risky knowledge is to have an old pro shooting down your dumb ideas and explaining the mechanics of why and what-instead, full-time, for a few years at a stretch. For the record, I don't even work in residential now, but for a clearing contractor to an electrical transmission company, so I'm not trying to create business. Too many people get hurt, not understanding that they didn't understand the problem space well at all.
