< About how I try to learn to use Vim
Nowadays I use neovim on my own machines, mostly because I am currently interested in learning Lua, so playing with the API to make little tools has been a fun way to learn. But on remote servers I use vim or vi/nvi mostly since they are ubiquitous.
What do you mean by using flashcards? It seems like you would be better off going through vimtutor then just jumping in an using vim exclusively---with an easily accessed reference for when you forget a command/key.
That said, I feel similarly to what inquiry said in their comment. Once you get acquainted with vi-isms, it becomes second nature, like riding a bike.