I agree with most of this, but am perplexed why you said it in response to my post. I simply remarked that you're always in a position, so practice or not, you have to decide if that position is what you want to be in. I totally agree deliberate practice is the way to go, see my post earlier in this thread where I made remarks about that very thing, ... but whether you have that deliberate practice or not, you have to take a position. I think a reasonable argument is to say that you should limit your time frame if you don't know what you're doing, meaning that you shouldn't actively trade on short time scales unless you really know what you're doing. Without practice, sticking to dollar cost averaging, etc, or choosing a mutual fund might be the best you can hope for, because the more you trade the more you're probably going to lose if you haven't practiced deliberately to trade actively. The more active you are as a trader, the better you need to be to avoid losing your stake.
I've read that book. It's interesting, reminiscent of Gladwell's work on talent (book?). Key point in Little B of T is - type of practice is critically important. Practice what is both difficult for you and useful for the task. That's how the greats get great - shooting 100 free throws AFTER practice every day - if that's their weakness.
I thought the key to this quote was the "deliberate practice'. To me this would be a particular aspect and sculpting the practice exercise to develop or hone that aspect/technique.