Having been a floor trader, I can say that the floor teaches you specific skills for that pit, but also some general things about assessing market action: Is the bid or offer being hit, are the spreads bid, where are the commercials bidding/offering, where are the locals positioned/bidding/offering, what are related and even unrelated markets doing, and on and on. Is this useful, and can it be transferred to the screen? Yes and no, and that's a whole 'nother discussion.
The problem, as I see it, with all trading, is that there is a progression to go through that is somewhat unlike learning other skills. Think about the comparison to learning a musical instrument.
The first thing one needs to figure out is what to DO. Since there are any number of viable approaches to trading, people spend a lot of time sorting though these. Books are written, for the most part, by people who's methods worked once, but would not work nearly as well now (ala Market Wizards), or by people who don't really trade much, but write a lot. Think about it: if you had an edge, would you write about and sell it in a book? This leaves chat rooms, anonymous web sources and fora, and so on, mostly populated by those who don't know; just read any sampling here on ET.
In playing, say, the piano, it is reasonably easy to figure out how to start, how to progress, and what to practice, and this leads to the next issue discussed here - practice.
Without know what to DO, it is very difficult, if not impossible, to know what to practice. So whether "deliberate" practice or any other kind of practice is important, or whether 1, 2, or 37 years, or 10,000 hours are necessary is an irrelevant question if one does not know what to do. For the vast majority, this is where the quest ends, or simply devolves into an endless and pointless loop: Read or hear about something, "test" it some some way (usually backtesting), try it, find it doesn't work, and then repeat with a new idea or approach.
Another problem is that markets, due to technological advances, varying efficiencies, economics, politics, and multiple other inputs, change over time. Trying to fight today's and, importantly, tomorrow's battles with the weaponry and tactics of yesterday's battles may not work well at all (and usually doesn't). By contrast, the violin does not constantly add and subtract stings, lengthen or shorten the fretboard, change tunings, the musical keys do not change, and so on - this is a fairly static environment compared to markets.
Is this commentary some sort of answer? Not really, just an invitation to think about what one is really up against when attempting to learn to trade. In my experience, it's figure out what to do, practice this, then be able to adapt; i.e. figure what to do all over again, then practice this.
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