What did you learn from TI?

Had to think about it.
Not much, but focussing on the action of the recovering arm instead of the pulling  action did give a change of perception and can lead to some positive things.
Also liked the more energetic arm throw forward action although that was more a Boomer thing than typically TI.
Without establishing a proper anchor all these actions feel a bit pointless.

Zenturtles post "don't ever leave your scapular plane" was very important for a start. Taking the arm too far back at the shoulder is tempting but disastrous.

It helped me understand my tennis strokes better too.