My experience(s) of CBT would suggest that certain techniques used in CBT can be… not necessarily the most helpful tool, always, for a certain type of over-thinker.
One way it can be unhelpful is this sort of thing: for me, some aspects of CBT led to prolonged mental arguments in my head between the "original" thought (e.g. "I am a burden on society who has never contributed anything, only consumed other people's energy and resources") and the "new, improved" thought I was meant to replace it with (e.g. "It's not necessarily important to contribute, and maybe I've contributed without realising, and maybe I haven't contributed much of tangible benefit to society yet, but I can work on that in future 🙂🙂🙂". These arguments between my original thought and the replacement thought usually ended up encouraging my brain to sharpen and hone its arguments for the original thought, strengthen and bolster the original thoughts with better, tighter arguments against the therapised, CBT -approved thoughts.
And, particularly if you're seeing someone with a fairly basic level of CBT training without much other psychological background, or who hasn't worked with many autistic people, or if you're working by yourself from a workbook or a computer programme, CBT often works on certain assumptions as to how human beings think, which may not work well for anyone who doesn't fit those assumptions, including autistic people (this can also cause problems where there are cultural differences).
I found the CBT model of the human mind — at least, the more cognitively-oriented part — fairly unrelatable. The diagrams showing the relationship between thoughts, feelings, and actions didn't make sense of what was going on in my head, no matter how long I tried. People with ASD have minds that work differently, but also may have different levels of access to their own emotions — alexithymia, or difficulty understanding/describing what you're feeling, is common in people with ASD.
Some of my inability to relate to the thoughts-cause-feelings model that the most basic versions of CBT tend to include may have been related to my bipolar disorder, rather than my ASD, though. CBT assumes that your feelings of depression or anxiety are a result of your thoughts. My subjective experience of my bipolar disorder is that the mood state hits first, hard and fast, along with the associated physical feelings, vegetative symptoms (eating, sleeping) and so on, and the relevant thoughts follow afterwards. One of the types of anxiety I experience is much the same. I get a feeling of continuous anxiety, which is intense and lasts a few weeks. It's only then, shortly after it hits, that my mind generates thoughts in an attempt to explain why I'm feeling so anxious.
The other thing is that a lot of CBT, at least in the simpler self-help, IAPT or short-course CMHT versions, is essentially "change how you think to change how you feel". For people with ASD, changing how we think can be really, really difficult. People tend to use words like "cognitive rigidity", but I believe it's more complex than just stubborn inflexibility. Either way, once someone with ASD has a certain belief about the way things are, for example that they're unlikeable (a belief that's easy to acquire going through the ability system as an autistic person), CBTing that away may take a lot more work and a lot more time than IAPT (or NHS Talking Therapies, or whatever it's called now) and therapists are used to it taking, and that clients may be led to expect.