Here's my experience with it. In the 1980s, guys were showing up on fires with brand new saws and claiming to be fallers. Forest Service people--falling bosses go out with contract fallers on fires and help out and watch things. These falling bosses were having to return to camp after just a few trees were cut, or attempted to be cut, with the "faller" in tow because the fallers were incompetent. We were also having fatalities and injuries during those years. We had a fatality on our district--a motorist driving by was killed when a hazard tree being felled, went over backwards, and hit him as he drove by. The guys out doing the falling were well versed in falling, but not safety. No flaggers were present, no warning signs, and it was a fairly well used road. That's why the certification started--too many injuries and deaths.
Douglas Dent videos were watched, then one went out with the district expert and started cutting trees. Dent actually went out with some of the local Randle area production fallers to film. I remember them coming into the office afterwards and talking about having a couple of the trees go over backwards that day and having blown the filming of the falling method they wanted to demonstrate.
Various experts in and out of the agency got together and came up with the certification.
When I got my "permanent" job, I got a call asking if I would want to start work on a precommercial thinning crew. I said yes. I showed up, was given a beater saw, file, chaps and earplugs and told "Don't get hurt." No training. Trial and error was the way I learned and some of the trees were big enough to maim or kill--culls had to come down. I did go get a coworker to cut some of those as I did not know how to do it. I still don't. Found out thirty some years later that the guys on the crew had a pool going on how long I'd last. I made it through the season and was able to cut as much as they did after I figured it out. And, I had to use the chain brake because the old Mac saw I had wouldn't run unless I kept the idle speed turned up.
The bucking exam I had later in life was going out with our C faller, and bucking and limbing what he told me to do. The same was done with the volunteer organization, except with the latter, I sat through a class before going out.