Setting aside the 7th chords for now, the other chords I need to learn are C Minor, F Minor, G Minor, Bb Major and Bb Minor, and I learnt these through a similar method I use to teach my 1 on 1 students how to tongue faster. The excersise traditionally is starting at a slow tempo (I used 40 bpm), play a long note for 4 beats, then 2 for 2 beats, then 4 notes for 1 beat, 8 notes for 1/2 a beat each, and you keep going until you can’t tongue faster. To learn these chords I substitued tonguing for a chord change, so it was 1 chord per 4 beats, then changing chords every 2 beats, then changing chords once a beat.
These are the chord shapes I used;
I stopped the excersise once I could comfortably play 1 chord a beat at 60 bpm and I recorded this video of the excersise once I could comfortably play these chords at that tempo.
Hamish Reeves Music 