Sometimes I talk about hypnosis as if it's "cheating". There are no actual rules against using trance, but there are a couple reasons to take a different approach.
"Cheating" requires that you get them responding to "hypnosis" first, which is a nontrivial constraint. The second bit is that hypnotic trance is a fancy way of saying "shut the fuck up and listen". While they do need to listen, you also want them to voice important objections - if it's important it'll just come up again later and undo your work anyway. So I kinda see trance as a crutch - at least for the set of goals that are good for the subject.
You still gotta find out the structure of the problem, and it's a lot easier to talk than to ask yes or no questions to a ideomotor twitch. You still gotta get them to shut up at least a little, but there are conversational ways of doing that without some bizarre ritual about looking at your hand and saying the names of colors.
I've been doing better at this lately, and I'm a bit giddy about it. I've been weening myself off, using hypnosis to take out one piece of the puzzle, or sometimes just going pure conversational. I wish I could say that I learned something new, but I think it's just applying a few obvious-in-retrospect ideas.
If you squint your eyes a bit, it can look like we're just "reasoning" people out of problems that we're "immune to reason". And that kinda is what's happening - it's just that we're using a different kind of skill. Most people that give up in frustration and exclaim "They're immune to reason!" are trying to out debate their "opponent". The skill isn't in cornering an intentionally dodging opponent. The skill is making sure they're on your side and are actually following each step of the way. If the actual beliefs are dissociated from the argument module, then no amount of maneuvering to corner the argument module is going to help. Your words need to move beliefs and aliefs together.
I had been having trouble getting lasting (deep) changes without hypnosis, as they'd say "oh yeah, of course", and then I'd feel stuck - how can I make more progress if they're already convinced? The answer is surprisingly simple. If their body language and tonality suggest that they've not actually changed, then call them on it - don't pretend to believe them. There are different ways to do it of course, but I've had fun just repeating the same question until they sound like they mean it. You need to get them in touch with the problem issue, and they avoid this by pretending it doesn't exist or that they can't change it. Call them on these lies. Often they'll claim that they're not lying. Call them on that lie too. They don't really believe it, they just pretend they do.
Another big issue is people not following your line of thinking - trying to jump ahead and bring up possible objections instead of sticking with it. If you follow those even long enough to disclaim it, you lose. If you do that, they can distract from the distraction, and if by some miracle you get it to stop, you still have to wind back. The right answer is to refuse to follow their distractions. The other obvious-in-retrospect idea is that when they're being too disruptive to follow, call them on it! (thanks Joe) As long as it comes across like you see it as a real concern and its a matter of fact (as opposed to an opportunity to be accusatory or condescending), you can usually get them to address the meta issue of why they aren't following.
None of this is to say that hypnosis isn't awesome and useful - it certainly is. It's just that it's usually not necessary, and the strange voodoo rituals can be a turn off.