Playing with the Cameron Family Singers brought up that space when improvising with people in straight ahead forms of music like country or blues or certain jazz and you have to determine what the changes will be, as best you can from just the first sequences you hear, from maybe just two chords. You try analyzing intervals on the fly and bet on what the next ones will be. In those music school days I knew people who made that their job. Horns and violinists more often than not. I spent time trying to refine my own capacity to know intervals instantaneously but never won first prize. I can see its value just like those who swear by solfege. Not this lifetime. I love the situation of trying to do it all before a live audience, trying to upload the info of the first verse into my mind’s cpu and hopefully get it right in the next ones, feel secure about replaying the pattern. Sometimes I’m absolutely wrong and play the 4 or the 5 as loud as I can only to realize it was wrong and I ruined that moment for everyone. Sometimes I’m also right and everyone, including me, thinks I pulled a rabbit out of a hat.