Mnemonics are highly personal and I never use mnemonics created by others. There is also empirical evidence to show that they are more effective when you come up with them yourself, but I can’t find the paper in question after 15 minutes of looking and gave up. However, I suspect that this could also be because you spend more time with the encoding if you do it yourself, rather than read something someone else has written.
I think there’s a fair amount of misunderstanding about the purpose of mnemonics. I think it’s exceedingly rare for students to remember most of their mnemonics. I know roughly 5000 characters and if I went through most of them, I would have no clue what mnemonic, if any, I used when learning them.
But that’s not the point, really. I think mnemonics work well as a stepping stone to long-term memory. I might not need a mnemonic to write 想 today, because I’ve seen it thousands of times over the past decade or so, but I know I used a mnemonic to learn it back in 2007.
Mnemonics also work well for problematic and rare characters. I still use Skritter daily and often come across fairly rare characters that I would have no idea how to write if it weren’t for the mnemonic I have for them (and still remember; I almost never write them down). Relying on mere exposure for learning these would be almost impossible.
What I’m saying is that a mnemonic can be good and have served it’s purpose, even if you don’t remember it! I also think that if I don’t remember the mnemonic, even after looking at the character and its components, it was probably not good enough for long-term storage of rarer characters.
Finally, I would strongly advise against marking yourself as correct for any character or word where you have looked at the mnemonic. This can potentially create a situation where you know how to write things, but only in Skritter. That, I assume, is not the goal. This is why we have things like raw squigs for non-beginners, because getting used to having support you don’t have in real life can be detrimental for learning. For beginners, this is outweighed by the positive feedback from writing good-looking characters and that satisfying feeling when strokes fly into place.