Never heard the theory in as many words before but it makes sense... the forward momentum of the aeroplane will improve the efficiency of the propeller.
Regarding my Shoreham flight/fright (delete as necessary) I agree that with a normally aspirated engine always build up the power to avoid a "rich cut".
I have had a lot of feedback from that experience (one experiences of many I suppose) and I still remember asking my passenger, who was a Gliding Silver C, to drop the extra flap for me but he didn't know where the switch was... so, if you want a job doing properly...