I'm doing Mahasi noting with breath sensations in the nostrils as the anchor object. At this moment I'm verbalizing notes, but it takes a long time compared to all the sensations that I'm noting. When should I drop the verbalization and what should I use as a substitute? Should I mentally 'tap' the sensation or leave it at just knowing it happened? I think I'm stuck at dissolution and searching for a way to progress.

Yes, I used tapping or 'snapshots'/'freeze-frames' when I was at stuck points such as dissolution or mid eq.  Empower yourself to do whatever works and to follow your intuition. 

Labelling is a tool to know that you are doing your work and not getting lost in thoughts. So is "tapping", a lighter version of labelling. If you know you can do your work without needing these tricks, feel free to drop them; return to them only as needed.

Neko:



My personal experience was that mental labelling even when I had the instinct not to progressed me faster than going with my gut.