[levicole]

I really think it depends on what level you're at. If you're still struggling to identify notes on the staff, then flash cards are just fine. If you're struggling to identify the intervals or triads, also still fine. If you can do that easily, then forego the flash cards and start analyzing Bach chorales.

But I'll restate what I said elsewhere, I think ear training is much more important once you get past the basics. In that case, I'd learn the Nashville Number System (https://en.wikipedia.org/wiki/Nashville_Number_System).

[bajsejohannes]

I'm curious; why would you recommend the Nashville Number System over Roman Numerals (https://en.wikipedia.org/wiki/Roman_numeral_analysis)? Seems like the latter is much more widely used. Maybe I'm in a different bubble than you...

[levicole]

The Nashville Number System is faster to write down as you listen to a tune, has methods of indicating ryhthm associated with changes (underline means half a bar, diamond around a number means to play the note once and let it ring for a whole bar). It's just better all around for popular music. Roman Numerals are really only used in analyzing classical music as far as I know.

Part of my education, in commercial ear training class, we had to write number charts and get it right the first time through. It sounds hard, but with practice it's really quick.