I felt the same exact way trying to memorize molecular formulas in organic chemistry, being able to visualize the molecules and some outlandish pneumonics really allowed me to force my brain to make memories that I forgot over time however I gained the ability to "see" the molecules in my mind and deriving the formula became trivial.

Creating really unique pneumonics works similar to how you can recall when something happened out of the ordinary or have a "sixth" sense where you subconsciously can sense something is off in an otherwise ordinary situation or encounter. If I had to guess, this might be an evolved human survival mechanism that helped our ancestors detect and avoid dangerous/deadly situation.

I wonder what other evolutionary mechanism we can hack to encode concepts more deeply. I know spaced repetition is the mainstream approach via flashcards/ankii type apps. I think pneumonics blended with spaced repetition is the most practical methodology. Thoughts?