A: NLP has many patterns or techniques. And they can be very effective when used the right way. Let me clarify this some more. NLP works because it systematically reorganizes the "how," the process.
Something triggers a particular sequence into play, and then something else triggers it to stop. Using NLP, or better stated would be, a person skilled in NLP, would piece this strategy apart to discover, how it works, when it works, what triggers it to start, and what triggers it to stop, as well as what beliefs, decisions, and other rules keep that strategy in place (because some patterns come and disappear without any conscious awareness at all--no rule to keep it there).
Once you have all this information, the technique or the intervention takes only a matter of minutes. Everything up until this point is where the work is. All too often people learning NLP in the early stages try a particular pattern on themselves and conclude, "Oh, this doesn't work on me."
In most cases, this is because a pattern is run on only the conscious information of the problem. And then it is just about as effective as someone trying to use willpower to stop doing something. It doesn't work all that well. Eventually, your conscious attention shifts and your unconscious patterns emerge once again.
So the answer to your question can be none or all, it just depends on how you are doing what you are doing.
-Oz