I had my CFI work with my wife for a few lessons, we didn't call it pinch hitter but we did outline a basic training idea that wasn't the end goal of getting her PPL. She had gotten spooked during a cross country flight when we ran into some turbulence. A front had gone through the night before and it was fine the first hour or so but the last hour was bumpy as heck. I tried climbing and slowing down but I couldn't find any smooth air, I offered to land but she said she was OK. We were never in trouble but it was bumpy as heck. She almost didn't get back in the plane for the return trip a couple days later, which turned out to be a smooth ride all the way back.
She did a lot of pattern work and basic maneuvers but it took her 7 or 8 lessons just to get where she wasn't scared to death. I don't think she ever landed it completely by herself. The last lesson or two, she finally started to learn but she had to return to work and has been unable to "find" the time for more lessons. I really wanted it for her much more than she wanted to study and become a pilot. You can't want it for anyone, at least now she is comfortable flying with me. I think she could get it on the ground if she had to do it, her approaches are flawless and she can fly the plane...somewhat.
I think it's a good idea for anyone that is going to fly a good bit to be able to handle the basics of maneuvers, traffic patterns, stalls, radio communication and especially landing. Pinch Hitting sounds like a good idea to me.