Well +TSRA you bring up an interesting subject.
So lets look at it using logic.
We will assume that in your early years of flying had held a flight instructors rating and let it lapse for thirty or so years.
However as your career progressed you had enough experience and teaching skills to have spent years as a TRI/TRE.
Then in your retirement years you decide to go back to ab-initio flight training do you think that you may still remember the basics of flying or have you completely forgotten the basics?
As I have previously related here on Pprune according to Transport Canada the fact that I had acquired decades of flying experience outside of ab-initio flight training it was going to be more difficult for me to renew a flight instructors rating than a 200 hour new commercial pilot.....because I now have to many preconceived ideas about how to fly which I would have to unlearn.
See their logic?????
