It's called Koch's method.

http://www.justlearnmorsecode.com/koch.html

https://www.qsl.net/n1irz/finley.morse.html

I'll have to try that. I've tried some acoustical training before, but not starting at full speed like Koch's method.

Once you learn all the letters, as you walk around, pick various items you encounter, and say their name in Morse code. A car: "dah-dit-dah-dit. Dit-dah. Dit-darrrr-dit."

For fun, pronounce "R" like a pirate would.

Thanks for this one. I haven't heard this suggestion before. I'll keep that in mind if I ever try to pick it up again :)

If you talk to old school CW operators, they will all tell you that you need to go beyond the letters and into the words and sentences like you skim over a paragraph. In fact, if you operate morse too slow, many of these old schoolers don't want to talk to you as you break the "flow". Which is the exact thing you're wanting to achieve in morse fluency.

It's just like a language. If you want to read morse code look at that chart, but if you want to hear it quickly you'll need to do audio flashcards. I n Anki it's pretty easy to add cards that have no text but sound which should be all you need.