Thanks for posing the question, @Jaden_Kim! As others have commented, our goal in IFR is to give you the understanding and the resources to make these choices yourself. There is no single right way to think about a tune like All the Things you Are. Bringing all of those sounds onto a single tonal map can illuminate certain things. Breaking it up into several different keys can illuminate other things.
With most songs, I personally prefer to visualize everything on a single tonal map wherever possible. I am quite reluctant to “move my 1”, because I find it so empowering to be able to picture all of the sounds on a single tonal landscape. But even I wouldn’t insist on this approach always, and this particular song is one of the best examples of a song where this approach becomes unnecessarily complicated.
But I also don’t like having to memorize chords using the absolute note names. I always want to be thinking in tonal numbers because this is what keeps my ear engaged and learning, and it’s also central to the way that I’m able to express the sounds that I imagine. So for a tune like this with multiple key changes, there is a hybrid approach that works the best for me.
This hybrid approach is to go ahead and mentally switch to different keys throughout the tune, but to remember those keys by their tonal relationship to the original key. For All the Things You Are, this works out to be the following keys:
key of 1 (the original key of the song, which is Ab in most fake books)
key of 3
key of 5
key of 7
BRIDGE:
key of 7
key of #5
FINAL 12 BARS:
key of 1
If you like this mental shorthand for remembering the key centers, sometimes there are interesting coincidences you can notice which help you remember where a tune goes. For example, in that first section with all the key changes, notice that we go to the four key centers of 1, 3, 5 and 7, which are exactly the notes of the 1 chord. I don’t believe that there is any meaningful connection between the key choices and the notes of the 1 chord. But it’s a nice coincidence that makes it very easy to remember where this tune goes.
I should also say that if you practice the IFR fundamentals very deeply, you will develop such a strong ability to orient yourself in the key of the music that you can quite literally forget all of the above and just play. When the key changes, you’ll feel it. And if you just listen to whatever note you’re playing in that moment, you’ll know exactly where you are in the new key. I described this experience in much more detail in Exercise 5: Free Harmony in the book Improvise for Real. So this is another technique that we always have available to us. Even if we don’t know the chords to a song, we can always approach it as an exercise in free improvisation and just respond to what we’re hearing in the moment. But since it’s nice to know ahead of time where the harmony is going, you might find the hybrid approach above to be a useful technique.
Thanks for starting this important discussion and thanks to everyone who has contributed.
David