Story time...

A TALE OF TWO NEWHIRES

Our characters:

Skippy, a 450 TT, 150 as CFI (which he didn't think was good experience for flying an airliner)

Capt. Jack, a grizzled, oldtimer with several thousand hours and a paper (before holograms) ATP certificate

Skippy and Jack were sim partners.

The first sim session, Jack handled the aircraft well, and his knowledge of the istrument enviornment impressed the instructor. On the other hand, Skippy was all over the sky: he was so far behind the aircraft, he couldn't enter a hold.

Over the next half dozen sim sessions, Jack's flying changed little as it was already ATP level, but he still learned much having never flown 121. Skippy, however, showed huge improvement... even to the point Jack had to admit the kid could handle the plane better than the old veteran.

At the end of the week of sims, both passed the checkride. And lived happily ever after.

The End

True story.... (I was Capt. Jack). When all was said and done, my partner flew as well or better than I did.
BUT, since he had never flown in all four seasons, or in different parts of the country, or any of the other "intangeables", he missed things like operating de/anti icing equipment, entering holds, choosing one procedure turn over another, adjusting speed/altitude/time to make crossing restrictions.... the stuff that I never had to think about. That is what one gets with experience.