This is the same band that did "Live at the Plugged Nickel" and you can hear quite clearly from that, that they did just go where they wanted - with no reference to the changes necessarily.
It was the fact of having a regular quintet that played together so much that they could follow where they were going and hear what the others were doing and go with it! Plus they were all such good musicians, of course!!
That's one of the reasons that quintet was so influential and so many bands do this kind of thing now, that I almost take it for granted that that's what Jazz is all about - but back then, it must have been truly amazing and shocking, to see them live!!