I think that you are correct. It reminds me of when I had a government job for a few years. Pretty common there.
Again, he's earned it IMO but I really prefer a fill-in but perhaps the thinking is that new listeners should hear a recording of the real thing.
I’m pretty sure the stations don’t like it when he does this. Dunno how the contracts are written, but I am sure the Doc doesn’t get as much money for re-runs, full or partial.