> In most subjects I have found ChatGPT to be fairly reliable.

Not the OP, but I am very curious what subjects you have experimented with and whether you used any special prompt techniques.

My experience has been quite on the contrary: on the few subjects I have some understanding of, ChatGPT appears to do fine for basic questions and attempts to summarize concepts at a high-level, but any attempt at drilling in to specifics seem to cause it to hallucinate quite a bit, particularly with regards to concrete facts or citations or anything of that sort.