I did not see any improvement, (the second time things briefly got worse), but I admit I get frustrated quickly, and did not stick with it long enough. I was never sure I was "doing it right."
Thought about trying again, at home, but I don't know what is safe to try. When this started, I'd bought a neck pain book (written in the early 2000's) that had example exercises. I showed the 1st physical therapist (a PhD), and he said "Oh no, don't do those exercises, we don't do those any more. That will make things worse!". So I'm leery of trying random youtube video exercises... and due to Covid, not quite ready yet to go to in-person PT again.