The problem is that my informal surveying suggests that most people are indeed led to believe that 91.205 is all there is. That's the problem with elevating 91.205 to special status bu forcing it to be memorized.
Over the past, oh, 10 years or so, I've periodically posted a simple question in various pilot forums asking about the airworthiness of an airplane with a specific piece of equipment missing that is not covered by 91.205. I also include an inop equipment question when I do flight reviews, and even checkouts for people I haven't flown with.
The result has been that those who learned the burning fruit or disturbed cat mnemonics are more likely to get the question wrong than those who never even heard of it. I've even seen CFIs get it wrong.
To the original question, the only two mnemonics I will even refer to in teaching as being somewhat useful for some people are GUMP (the original, no extra letters) for complex aircraft and the 5-Ts (not 6 or 7 or 22) during instrument training.