GOL gives a guideline how to get an "typical, easy average" (regarding height, weight, spread, crown form, lean, slope, soil conditions, temperature...) tree down, usualy the hard and sometimes kinda exhausting way into usualy the easiest direction-but with a bonus of that even someone who knows *rap about wood, its mechanical properties etc. can walk away, or has time to haul his *** out or at least is not directly in the way of the mess as it propagates. GOL was meant as an entry level survival kit for the easy tasks to learn from. But some people, esp. desk rats who have never been with saw on sloped ground, consider it "the only safe practice", because they don´t know a s*it about some of the troubles of real logging, or they make good money on it under the safest and easiest conditions availible.
How GOL and reality in all its width availible comes together can be easily ilustrated on snaging. Snaging-considered (and for a good reason) as the most dangerous falling task. Take a bit leaning oak snag some 50´ in height, perfectly sound and solid, with knotless butt, just the bark peeled off and dry as desert sand. Try the 1/3+1/10 rule with plunging and strap-almost sure the thing won´t even budge. Try to help ´er with wedges-and when it´s freezing, there are chances the barberchair will snap your head off with no warning at all.
This is why GOL emphasizes heavily that snag=hazardous tree=experienced faller job.
I grew up snaging with handsaw-for wood for my projects, for firewood. I taught myself using chainsaw snaging for firewood. Had a GOL instructor seen some things I´ve done, he would´ve tried to stomp me into ground, because every move I did was against GOL. And I swear, had someone try to make me use GOL on some of those trees, he wouldn´t have survived that-because of me wanting to live another day. Pushing GOL as the only possible way and as a "one fits all standard" is kind of equivalent to murder atempt in my books.
BTW, this site and threads like this was real eye opener and I owe at least a beer to most of the contributors. I do not regret any single minute I put into reading all those 460 or so pages back, several years ago.
Northmanlogging is damn spot on. The ash woodfarmer showed with almost barberchaired buttlog is like 16-18". Now imagine the plank GOL considers a safe hinge here-like 10"x2" piece of wood. Or the 32" fir northman mentioned, like 18"x3". Pretty beefy piece of wood, huh? Now try to bend this, but not over some 6´lenght as if using it as a service ramp for your truck, but at kerf width. Or, if you saw off the heartwood in the fir, it makes for spot bending two about 5"x3" posts (most house framing is done with 2"x4"...). Seems absurd? But that is what GOL teaches.
Experienced faller sets the hinge width after asesment of "how thick a plank will support the weight of the tree" and "how thick a plank will bend and shear by the weight of the tree, while standing the abuse of branch contacts and swing forces during fall, without tearing and messing the butt".
I find myself computing with yield and tensile strenghts of the wood under the saw very frequently, with some experience-earned coefficients for soil, season, fungus/rot damage... This needs a helluva lots of falling done, or some combined carpentry and scientific lab background to get an idea about how the wood behaves under different loads and scenarios.