1- the better you hand fly the better you understand automation
is not exact, I agree. It should be ammended as follows:
...the better you
may understand automation.
which means that if you don't study the books frequently and learn from experience and keep studiying from time to time, you will never fully understand your automation.
If you lack hand flying skills (for instance because you hardly have flown a few hours in a cessna, after which you directly came to the jet airliner and only hand flew it a little bit in the sim) automation becomes a "black box". You insert inputs, and outputs are the result, but you don't understand how things work inside the black box. That is, in my opinion, inacceptable from a professional pilot.
I sometimes get surprised when fellows with over 2000 hours on a jet demonstrate a very poor understanding of the principles involved in flight and how they have a lot of misconceptions about automation modes.
If you come from another jet airliner that you did fly manually frequently, then you will understand easily any automation, as long as the aircraft still has wings and engines.
The following, I think, are requisites por a transport pilot:
1- master your automation
2- don't be afraid of hand flying (no AP/FD, no A/THR)
I think that regular hand flying practise is good for both