I just finished a three day prefectural run course to get a chainsaw and tree cutting certificate, a requirement for work paid by taxes, and prompted by many people being injured over time. The manual stressed ultra safe procedures, but oddly, one handed use wasn't even mentioned. They weren't teaching cutting when up in a tree. There were things in there that were taught not to be done, like if you have a hung up tree what not to do to try and get it down. Some of the don'ts though potentially hazardous, are what professional people can do safely. At first I was a little frustrated that they would be teaching against things that if approached wisely, work, but then over the entirety of the course I came to a perspective that teaching ultra safe ways to people with limited experience was not a bad thing at all, especially when it came to observing how about half the guys in the course were pretty much totally unskilled in saw use and how to cut down a tree. How a person may diverge from the ultra safe with experience is something else, but I could better understand how safety was by far the priority over speed when getting people into tree work. If they had also taught against one handed saw use, I could have understood that within the context of the course. It doesn't seem extreme to tell beginners to avoid that. I'd forgotten how uncoordinated beginners are with a saw, and basically with very little sense about what is safe and what isn't.