It would seem to me, that as in anything we wish to be great at, practicing
ANY aspect of flying that you normally don't encounter or do regularly improves
your overall knowledge and skills.
"Proficient" and "Expert" are certainly not the same.

Besides "learning to fly", I play guitar and other instruments.
To become better at playing guitar, I often practice things that aren't
really played in songs when I play a gig. What it does is make me better
at many other things - "mastering" the guitar may be impossible to
a part-time guitar player like me, but pushing myself to do things I might
not has certainly helped me play better.

Whether it is physical or mental, that sort of discipline is, in my opinion, an
outstanding trait and shows a true desire to be as good as you can be.

Now, maybe there are those who don't want tor need to be that good, but "need"
is something you never really know about.

Anectodally, Israeli AF pilots learn about systems and engineering of their jets and planes
to better understand the entire aspect of flying. In a marginally humerous story (from
"Raid on the Sun"), when the Israeli's were learning the F-16 at Hill AFB in Ogen Utah,
they asled so many engineering and systems questions, some suspected them of attempted
espionage, when in fact they were literally just doing things the "way they learned to".
This helped them later modify and affect the Falcons for their raid on the Iraqi nuclear plant.
Interestingly enough, many of their question could not be answered by the USAF pilots and
trainers, and ended up learning a lot of important aspects of the F-16 from the Israelis.
The analogy? Is there such a things as "over preparation"?
Were they better pilots for this. I'd argue yes.

And, in the end, when you're in a commercial plane or in another situation where your
life is in someone else's hands, would you want that pilot to be "proficient", or possibly
"over qualified".

That's my 2 cents . . .

Now I expect people (as usual) to poke holes in everyrthing I wrote, according to the unwritten
Newsgroup laws that exist somewhere. and somehow, someone is going to take it personally
and begin to flame me unconditionally, whereby someone will rise up in my defense and create
a 3-month long posting under this Subject that, in the end, results in life-long animosity between
otherwise respectable people who have a lot in common - ha ha!