Shinzen describes in detail a spectrum of practices (in his "what is mindfulness document"). He doesn't really talk about speed so much, but it would seem that across the spectrum it goes from fast to slow.
Noting need not be accompanied by labeling, and labeling may be mental or spoken. This gives us three
possibilities:
1. Just Noting without intentionally labeling.
2. Mental labels accompanying the Noting.
3. Spoken labels accompanying the Noting.
Within the spoken labels there are three sub-types:
1. Sub-vocal labels (mouthed, whispered, or sotto voce labeling that would be inaudible to people near
you.)
2. Ordinary spoken labels.
3. Strongly spoken labels.
9. Can you summarize some basic guidelines for the labeling process?
Answer:
• If you are noting without labels and are getting spaced out or caught up, start to mentally label.
• If that doesn’t help, modulate your mental voice to be more gentle and matter-of-fact, even if that
seems artificial and contrived.
• If that doesn’t help, speak the labels out loud in that gentle and matter-of-fact tone.
• If that doesn’t, use strongly spoken labels.
• If the effort to speak the labels causes uncomfortable reactions (resistance, emotion, and so forth) label
those reactions. (Those reactions are proof that you’re doing the procedure correctly. The stronger
labeling mode is forcing you to go toe-to-toe with the unconsciousness itself!)
10. Question: I don’t like to label.
Answer: The solution is easy. You don’t have to! Labeling is an option
within the apparatus of Noting. But if it’s a choice between effortful labeling on one hand and being grossly spaced out on the other, go for the labels!
Personally I switch between them depending on my concentration levels, along the lines of what Shinzen suggests. If I am really concentrated (e.g. a good samatha session beforehand), I tend to do more non verbal noticing (and generally the more concentrated the faster), but when my concentration has gone to shit and I am getting caught up in thoughts I note out loud.
