If there is such a thing academically/intellectually as a "young (wo)man's game," the question for those of us so enmeshed becomes: why continue to specialize in middle age?
Galenson's thesis in Old Masters and Young Geniuses supports this thinking. "Experimental innovators seek, and conceptual innovators find," the latter at surprisingly young ages and often never again. Hence, no matter what we've found (or not) as an adolescent, perhaps middle age is our cue to start seeking.
Put another way, it is interesting to consider whether there are discernible landmarks of achievement lying afield of Gladwell's 10,000 hours. Where in the outer reaches of the life cycle might they fall? And what, then, about the relative worth of, say, 50,000 hour mastery in comparison to a broadening of horizons 500 hours at a time? Perhaps the latter might enable the 10,000 hour master to apply his or her already-substantial achievement to a wide range of immediate, human problems; and indeed, to better understand of his or her own accord what exactly constitutes an immediate, human problem in the first place? I will always be the first to make room for supreme achievers in the Bach or Coltrane mold, but I have had to accept that I am simply not wired for that path.
Glenn Gould famously blurted out something that every music teacher has thought to themselves when he remarked that he could explain everything about playing the piano in a half-hour while the student could spend the rest of his or her life applying this knowledge. Certainly 10,000 hours of practice sounds like a good minimum target for aspiring Professors of Applied Music seeking to unpack the technical and historical vicissitudes of their respective instrumental traditions; it is also wholly inadequate when it comes to mastering the composition, delivery, and contextualization of their own half-hour lectures. And so it must not be regarded as a mere formality, as it seems to have been throughout much of American academia for a very long time, that the latter and not the former is what these Professors are *actually* paid to do. Clearly some extra seasoning is in order; and if simply having Life Experiences® was all it took, every washed up conservatory brat would be magically transformed into a master teacher the moment their teenage child(ren) became sufficiently angsty to impose some long-overdue introspection. There would be middle-aged gurus in designer workout clothes falling from proverbial trees. We can only wish it were that simple.
Anecdotally, I have seen many peers (and myself) become increasingly unable to sustain the multi-hour instrumental practice regimen of college music school into early middle age. Those of us who at least met the barest of curricular time-banking expectations along the way and have continued to find smidges of focused practice time on a daily basis eventually backed into rather than charged into the 10,000 hour club, with all of its privileges and obligations, and with no hope of ever reaching whatever further thresholds might exist in the Gladwellian great beyond. When this first became apparent to me I took it as a serious blow to my self-esteem, committed as I was for many years to an intense practice regimen at the expense of virtually every other facet of personal development. I wanted to be a 50,000 hour tubamaster, or at least I had tried very hard to convince myself that I did. Further, though my hands now covered my face, I couldn't help peeking through my fingers at peers for whom the onset of Real Life® seemed to mark not just the end of their musical development but their personal development as well. It was both a shock and a relief to emerge from such twenty-something doldrums to find that my own desire for personal development had not abated along with my inclination to prioritize tuba playing over all else; and so I decided to listen to what my brain and body alike were trying to tell me: "You're already a specialist, and unless you throw your horn off a bridge, you'll always be one. Now go make it your own."
Just as most all of the principal players of the 20th century's greatest orchestras would fail to advance beyond today's preliminary round auditions on account of their individuality, so too would the areas in which many of history's greatest minds made their lasting contributions today be considered "beyond their competence" on account of vulgar credentialism's logic of accountability. To be clear, I do believe that membership in the 10,000 hour club is a necessity, and that eclecticism is a decidedly members-only area. But given that this number is pursued in a timely enough fashion for its own inner logic to hold, there ought to be plenty of life left during which to find a balance that meets your needs and fits your budget. So get to it.