Which is correct? "On Chords and Octaves" or "Octave exercise"?

Thanks in advance! Been playing about 5 years. In the "mechanics" section of lessons, Biegel and Durso give completely contradictory advice on playing mechanics. Both give sound rationale in their respective videos, but logically both cannot be correct at the same time.

Biegel advises an "up down" motion at the wrist to attack each octave, and literally says "curling the second finger may help". Durso, by contrast, specifically says to NOT move up/down at the wrist (forearm/wrist/hand move as a unit), and NOT to curl the second finger.

Personally, I am noticing fatigue and discomfort in my wrist after playing tons of octaves and octave shapes (Chopin's FI comes to mind), and that if I mimic a "locked", minimal up/down wrist it makes it worse. Biegel's advice, by contrast, produces no negative feeling in my hand/wrist. Any thoughts?