what makes it hard is staying in that mindset of opening and devoting yourself to the moment and the music, and giving up your preconceived notions and ego, while staying focused and paying attention to the most delicate details, rather than a technical skill issue
All of that applies equally well to carefully planned and structured performances too. Once you play a tune as band so much that you don’t even have to consciously attend to the physical execution, that is when your attention is freed up to listen and focus on hearing and responding in the ways you mention.
In my experience a well dialed in performance can be just as artistically liberating as a free jam
Well, it's on the list for tomorrow...if we play it, it certainly won't be as free form as if I were to call, say, "In Memory of Elizabeth Reed" in Db, or Impressions, or "Spanish Key", to be sure.