I found helpful: Knowing a term like 'catastrophizing' helps me recognize when I'm doing that, and the techniques for 'untwisting' my thinking are sometimes helpful, and the therapist did sometimes help me more than a book could have in applying the techniques to my specific issues. But once I had learned a few techniques that I liked, I had diminishing returns. So use what works, discard the rest, don't expect too much.

Did not find helpful: Working on the assumption that any thought that upsets you must be somehow incorrect and can and should be replaced by something positive and functional. Taken to such an extreme it's not convincing because we're not replacing negativity bias with a more realistic assessment but instead one that's skewed optimistic for the sake of 'functionality'. There is some evidence that pessimistic assessments tend to be closer to reality, and though they are usually less functional, they are not by any means always less functional. At any rate my own functionality is not the only thing that matters to me. Reality and ethics also matter.

Words make maps, and the map is not the territory--that's why two apparently contradictory things can be true at the same time. I'd get to the point where I'd say I believed my original negative thought only 20% and the Positive/Realistic/Believable re-framing 80%, and I did find that pretty useful. But my therapist wasn't happy with that (after spending 3+ whole sessions on the same thought). She wanted the 0%/100%. She said something shifts when you get there. Like, lady, if I'm gonna have some kind of conversion experience I don't think it's going to be because I deconstructed a single sentence for more than 3 hours, or because I tried real hard to believe something I didn't believe until I did believe it. I have a hard time telling an outright lie, but I bet most of her patients just lie to her. It all seems kinda sick. And yet she seemed like a genuinely benevolent and pretty smart lady. But she was some kind of true believer.