I've been an active CFI for 6 yrs and I can count my manhood how many flight lessons I had for less than 60 minutes. I'm sure folks do it and I could see it on a rare occasion, but I've never done it.
For example: even if the student meets me at the airplane and has the preflight done (which you couldn't do given your scenario), by the time I give him a quick brief on what we're going to do (a review from what I assigned him on the last lesson), start, taxi and t/o you're already 15 minutes into the hour. At my school I normally have to land 15 minutes prior to the next pilot's reservation to have time to refuel, tiedown, and do the recordkeeping necessary to turn the airplane over to the next pilot. If I didn't debrief, that's only 30 minutes of air time. Unless you polishing your landings, there's not much else you can do in 60 minutes.
I grew up in the military flight system and like them I believe the best learning is done in the debrief. It's not uncommon for me to spend as much time debriefing as we spent in the training area. On a 1.2 hr flight we might spend 35-45 minutes in the training area learning a new skill -- I could easily spend that much time talking about it on the ground afterwards. Especially when I'm introducing new maneuvers. That might seem like overkill, but when I compare the flight logs of my students to other instructors who are more interested in flying instead of teaching, my students learn skills in less flight time because of the debriefs. I had a pilot tell me once that you could write a book on every landing because there was so much you could discuss. I didn't believe it then, but I do now.
I charge for this debrief, of course. But I think it's a bargin compared to my peers who don't debrief on the ground. Instead, they debrief during the next flight at 4 times the price. They use this method: "Okay, turn west and climb to 3000 ft. Remember last week when we did stalls? The thing you did wrong was..." The airplane is the worst environment to lecture.
Just for comparison, we also sell tour flights for 30 minutes of air time. It's normally a .7 hobbs when it's all done. I give the passengers a 5 min brief on where we are going, the life vest, have them sign a paper and walk them to the plane. After the flight I skip refueling and simply tie it down and walk them back. It's a 90 minute evolution fro "hi" to "bye" for 30 minutes of flight.
If all you have is 60 minutes, go sit in the airplane and review your procedures. You can do that all by yourself and it's free. It's the best chair flying you can ever get. I always do that when I'm transitioning to a new airplane. I sit there and do checklists while mentally flying from the airport to the training area. I simulate engine failures, practice stalls, etc. 60 minutes of that once a week will make you a pro in no time.
Blue skies,
Rob