I don’t like mnemonics for batch learning (like WaniKani) to begin with, premade mnemonics arent as useful and there are still some issues with the mnemonics WaniKani offers you. Long story even shorter: They don’t work for me either. I don’t actively use any mnemonics for learning Japanese. That’s totally alright.
Personally I use [Userscript] Self-Study Quiz to drill newly learned items, sporadically over up to an hour after learning them. I’d give that a try. How much extra drilling you need to do is something you’ll have to figure out.