Noting-Technique: How many notes per second/minute?
As Trungpa Rinpoche explained, noting/labeling is done at the time of recovering from distraction, not all the time!

You sit and breathe and let your mind expand in its natural state, while the fishes of psychosomatic shadows swim deep under the ice, and then sooner or later one of the them raises up getting progressively sharper, becomes a fully-formed thought, then suddenly swallows you and carries away. As soon as you can, you notice that you got carried away, mentally label this very fact (silently saying "thought" in your head, or just making a mental note), and come back to just sitting. Makes sense?

You don't rigidly fasten the mind to the here-and-now, nor do you mechanically attach discursive evaluation ("thought" or whatever) to each and every mental phenomena. You give your mind some room.

This is like watching the airplanes do the touch-and-goes, you don't shut down the sky, you don't forcefully control every airplane, you wide open the sky and let them fly -- but when one of them tries to land on your airport and grasp you, you allow it to just brush your airstrip with its wheels, and then slip away letting it dissolve back to the pregnant emptiness it came from.

But if it does land and capture you, then by definition you are no longer watching. You can setup a subconscious alarm though, that will ring soon after you're caught -- and this is when you wake up, say "thought!", let go of the thought, and come back to watching.