Paul,
I still stand by my claim that the flight time to and from a training area can be useful. Especially in the early stages of learning.
As you said, a student is starting to fade at the 1.2 mark---this is actually earlier, more like 50-55 minutes of straight hard core learning. Way back when I was instructing, I used the short ferry times to slowly build up tthe lesson intensity, then about 50 minutes of solid learning followed by a gradual wind down on the ferry back for total lesson of 1.2 or 1.3.
THere is lots of stuff you can teach during the ferry, most of it airmanship--all that stuff that does not really fit into a stand alone lesson.
We always used to teach the CFI portion prior to the commercial checkride and utilize those hours---in fact, I rarely taught people commercial maneuvers except right before their checkride----they would be teaching me, right after they got their ppl or instrument.
As you say---choose your school wisely. At one of the supposed front runners in the US it would take an average of 7 minutes from the time you called for taxi to a pad to the time one got airborne. (I sat and timed it for two days a few years back).