In case you never heard about it (and for other people), these cards seem like the perfect thing to put in a spaced repetition [1] program like Anki [2].
The GNU Emacs manual includes a printable reference card, available separately here: https://www.gnu.org/software/emacs/refcards/
I use a permanent marker on a 3x5 index card, and write the command and key combo in black, and then a very "simple" explanation in blue. For instance, "SWIPER SEARCH" "C-c C-s" "inside files". or "DEFT SEARCH" "C-c n d" "across files".
Those index cards get pinned on my home office wall above my main monitor screen. Seems to help a bit for me, not sure if it would for other folks.
Here's a pic for the visually inclined! https://imgur.com/gallery/zlY5wYH