Reading MCTB, a lot of emphasis is placed on seeing very fast vibrations, quick noting, and so on.
This kind of emphasis seems to me to be unique of MCTB, since I never found it anywhere else, not in any tradition, not in the suttas, not even in this place.
Also, Mahasi noting traditional instructions seems to imply that noting once per second is more than enought in order to make some serious progress.
The Kenneth Folk detailed noting style goes even slower, suggesting that noting every two seconds is totally fine.
On the other side of the continuum, this advice from Tarin seems to imply that it's possible to make very fast progress doing something that is totally far away from any kind of "fast".

So, I was wandering, what is, in the end, that make the progress of insight happening?
What are the mental qualities (i.e. equanimity, strong momentary concentration, continuity of awareness, inclusiveness and so on) that are most necessary for the progress of insight to occur?