To 1.
I agreed is a way of training, but don't agree that is a way of training speed in most cases, and definitely not the only way to solve a block with speed. It trains you for strength, my whole point is you actually don't need that much strength as you need agility and flexibility. Most students that are blocked with runs in my experience have blocks in forearms and wrists, that get only aggravated by over engaging the fingers in the "high fingers" action.
Unless the problem with speed comes from "messy" playing, and then more defined articulation is needed, I don't see the point in training slow straining movements, that are not necessary to play fast. You still continue with the running analogy. I never said running. I always wrote walking.
Quoting William Newman,
The Pianist's Problems, p.49. : For utmost efficiency we must use the least powerful lever that will answer our needs.
To 2.
No, you didn't misread that I think it's a waste of time. I stick by it still. But I've always made clear that is
my personal view on it,
if you disagree, that is fine by me! Don't understand why you take it so personally. I've also made clear, everyone is different, has different needs etc. If it works for you, then great! Good for you. Not sure why you get so defensive. If it's offended you that I think it's a waste of time, have my sincere apologies that I didn't intend to offend anyone. I think though that it is not an effective method. You disagree. Cool.
I don't know who those "ancestors" are, but our ancestors also thought the earth was flat for centuries, and were wrong. That something has been done in the past, doesn't in itself mean is correct.
I found The Art of Piano Playing by G. Kochevitsky,
https://www.amazon.com/Art-Piano-Playing-George-Kochevitsky/dp/0874870682 a great read, which covers many of the pedagogical practices in piano technique through history. Not everyone had it right.
To 3
I agree with you, exaggerating movement is very helpful. I do it lots, I practice leaps a further octave a part, and practice in many different tempi etc etc.
However when you practice with high fingers, you are not really exaggerating the movement you need to play fast, you are doing a different movement, using your extensors. The moment you play faster, and you play closer to the keyboard, you are no longer using those, but the flexors, that you haven't "trained" if you only played with high fingers in the practice. Again, might not be your case, but the most common mistake is to try to do that large movement that is rising the fingers high, also later at the real speed one wants, and is in most cases that is not possible, because by the nature of the movement, rising the fingers is too slow. That incurs into tension and strain.
I can't but repeat, that every pianists is different and has different needs, I never intended to offend anyone, and most important of all, the first thing I wrote was to seek the advice of a good teacher, who should know best what that particular pianist needs at a given time.
Maite