Can you give examples of how that "LLM's do not think, understand, reason, reflect, comprehend and they never shall" or that "completely mechanical process" helps you understand better when LLM works and when they don't?

Many people are throwing around that they don't "think", that they aren't "conscious", that they don't "reason", but I don't see those people sharing interesting heuristics to use LLMs well. The "they don't reason" people tend to, in my opinion/experience, underestimate them by a lot, often claiming that they will never be able to do <thing that LLMs have been able to do for a year>.

To be fair, the "they reason/are conscious" people tend to, in my opinion/experience, overestimate how much a LLM being able to "act" a certain way in a certain situation says about the LLM/LLMs as a whole ("act" is not a perfect word here, another way of looking at it is that they visit only the coast of a country and conclude that the whole country must be sailors and have a sailing culture).