I've done it myself. There are some things that require concentration and effort, and some things you just have to let flow.
It's not, as near as I can tell the class of technique. Sometimes you focus punches and some times you just let them fly... but others, like dead hand technique, are ruined with a tight focus. Maybe it is the student and some students need to relax and others need to focus. Maybe it is the combination and student X needs to focus on his hip throws and relax on his sweeps and student Y needs to do the opposite.
Maybe it is something similar- in the 'make' techniques you focus on somatics, on the body and in the 'let' techniques the focus is on perception. Maybe.
It's on my mind today because it applies to other things. A new friend was asking about love- why it is so hard to find and so hard to keep. It's a big mystery to many, but I have never felt that way. Listening today I got the impression that finding love was a 'let' technique for this person and keeping love was a 'make' technique. That initial love was just supposed to happen and the work would come in keeping it from changing.
I approached it differently. Loving for me was a decision; staying in love has been an act of gentle perception, like turning a flower over in my hand to see something new every day.