> I am going to try to use this utility to help me generate the flashcards instead of writing my own logic. Hopefully it works well as it would save me a lot of time.

My favourite practise tool is slightly more complex than flashcards (but could still be implemented as flashcards). It's better for playing but still works for rote memorisation.

Randomly filled rectangular grids.

They are incredible adaptable and very amenable to generating with scripts or small programs.

e.g. notes of the A major scale:

Shuffle the notes and make them into a grid (here is a 7x7 sample shifting each row 2 places - although any shift of 1 - 6 places would work.)

    C#  G#  A   B   F#  E   D
    E   D   C#  G#  A   B   F#
    B   F#  E   D   C#  G#  A     
    G#  A   B   F#  E   D   C#  
    D   C#  G#  A   B   F#  E   
    F#  E   D   C#  G#  A   B  
    A   B   F#  E   D   C#  G#  

Play the rows from left to right along each row. Then right to left. Plat the columns from top to bottom. Or reverse it. Snake along the rows top to bottom from left to right, then back right to left. Play the grid in a spiral. Clockwise, then the opposite way. Play diagonal slices rising or falling. Concentrate on the first notes in each row/column - play the mode starting from that note. Make it a cloze exercise by removing columns (or rows or just random notes)

    C#  -   A   B   -   E   -
    E   -   C#  G#  -   B   -
    B   -   E   D   -   G#  -     
    G#  -   B   F#  -   D   -  
    D   -   G#  A   -   F#  -   
    F#  -   D   C#  -   A   -  
    A   -   F#  E   -   C#  -  

The adaptability is really limited only by your imagination:

e.g. Chords:

  Bm   D  Fdim C   Dm   G   Am   
  Fdim C  Dm   G   Am   Bm  D  
  G    Am  Bm   D   Fdim C   Dm   

Name the notes, play them (frets 1-5 then frets 5-10), play the triads, inversions, arpeggios...

Or the same idea but using roman numerals/nashville numbers and play them in different keys:

iii V viio IV vi I ii

Interesting. I wrote a silly little bash script that more or less did this, and then eventually realized I could do better for now by just printing out a bunch of blanks (keyboard) and making physical ones.

It's just too much work. Just doing it in one key is a lot, and you have to do that twelve times (fifteen if you want to be thorough and include all the enharmonic keys). So I am glad someone seems to have done it all already in a command line tool that hopefully I can automate.

Ha, I realized the way to make it "not" too much work is to only do them as I "need" them.

E.g. Find song, do I have all those chords? No? Time to make a new one.