Rather than tell you whether this course or that method is any good or not, I will tell you what I did as a 13 year old kid learning to play jazz. Back then they had this thing called radio, and there was a station that played jazz 24 x 7, and I listened to it. And every day I would get my horn out and practice my scales and arpeggios and etudes, and whatever I needed to practice for school, and then I would turn on the radio and play along with it. I was also playing clarinet, I had started playing clarinet a few years earlier, so I practiced that too. But I didn’t play along with the radio on clarinet too much.
My first paying gig was about a year later, still in Jr. High School, I got $5 for playing Acker Bilk’s big hit, “Stranger on the Shore”, at a school dance. On clarinet
. Funny…. I learned it from the radio, not the jazz station though. By the time I was old enough to drive, I was in a funk band horn section, and we played almost every weekend somewhere. We learned all our material by what we called “copping it from the record”. Today that’s called “transcribing”.
Of course I was playing in the school big band too, and I knew what chord changes were, so if I learned that this song had a Dm7 in it, I could figure out the notes. But I knew nothing about music theory until I went to college and they made us study Bach. And we used Walter Piston’s theory book. That helped me to cement my knowledge, and I learned why All The Things You Are had its changes set up the way they were.
The point of this is twofold - First, it’s important… scratch that, it’s
crucial to learn stuff by ear with no written material. Or videos either. Second, the whole is greater than the sum of the parts - there are many aspects to everything in music, there isn’t just one way to think of things, and there isn’t just one way to learn things either.
The last thing I will say is that many improvisation courses use the idea of “chord scales”. This scale goes with that chord. That’s an easy way to develop formulas and ideas, but I personally don’t think it’s useful. But you will run into it, so please remember that there are different ways to think of how chord changes work. So keep your mind open and try to allow your mental synapses to make new connections.