What's the reason for the high stump? I am always interested in the reasons.
As answered, you want to get above the rot.
In certain type of timber, you want to stand erect.
Makes you a smaller target, better vision and for better escape. Right?
You usually will see indicators of heart rot
( may have presence of heart rot conks)
You can 'sound it' with your axe, otherwise.
Your strongest wood fibers are at the ground in a healthier tree though. (When needed)
It shortens where the top hits but lengthens the travel. You can still gain 2 feet: on flat ground at that height.
It's also a good trick when you want to jump fences, now and then
That's a Swanson undercut, btw.
It's as wide as its deep. (1:1 ratio) 45° or pitch. A humboldt is 6/12 pitch at about 26°.
Humboldt is harder to marry up your cuts
but not as grabby in say Hemlock with a Ceder
chain but it's very dangerous in some hardwoods. It's just not wide enough.
Couple tricks I use in small Hemlock with big dogs is slam in first without the dogs. I actually do that anyway. Secondly, you can take 13° from the top and same on the bottom for a pie cut.
Tha all I know. Then I got expelled from cutting class.