To point number 1, I tend to think of flow as helpful but not necessary. For some tasks, I'm not really sure flow applies at all. I mean, I'm pretty damn good at tying my shoes. I do it without even thinking about it. I don't think flow was involved in learning that; it's just muscle memory. That's a trivial example of course, but there are other factors than flow which influence the effectiveness of practice. I don't think we should just give up if we can't have flow.
To point 2, you're right of course, but we can't be world-class at more than 1 or 2 things anyway. There's still benefit to being pretty good at something. A great phrase I stole from a blog called All Japanese All The Time is "You can have, do or be anything, but you can't have, do and be everything." If you want to commit your whole life to being say... the greatest chainsaw juggler in history, that's probably achievable. But you aren't also going to be fluent in 10 languages, an expert computer programmer, a world-class guitarist, and a grandmaster in chess.
I'm alright with only being an expert in things I'm able to devote full-time efforts to. But I'd also like to be pretty good in other stuff. How can I take bits and pieces of time here and there to achieve that? That's what I'd like to see some research (formal or informal) on.
I can't speak for others, but for myself, flow is definitely necessary. At least when learning something new or approaching a new problem. In the case of tying your shoes, once you've learned how, you might only spend a moment doing it each time and improving to perfection. But when you first learned as a child, you probably watched someone else do it multiple times, and sat awkwardly fumbling with laces for a (relatively) lengthy amount of time.
So if I have a running project in a language I am familiar with, I can spend a few minutes here and there making small improvements and honing my skills, but if I want to learn a new language, or just start a new project in an unfamiliar area, I would need hours set aside to really get into a flow. Scraps of time would never provide enough for things to click.
Basically, to more familiar the subject, the less time you need to accomplish something, the more efficiently you can use scattered time. So if you want to really broaden your skillset, it is very difficult when you have a 9-5 with a long commute, a home to maintain, social obligations/family, basic needs, etc.
I suppose that might mean that if you want to make efficient use of your scattered time to perfect skills, you would have to focus on your strongest skills when you have minimal time, and improve them to perfection.
To point 2, you're right of course, but we can't be world-class at more than 1 or 2 things anyway. There's still benefit to being pretty good at something. A great phrase I stole from a blog called All Japanese All The Time is "You can have, do or be anything, but you can't have, do and be everything." If you want to commit your whole life to being say... the greatest chainsaw juggler in history, that's probably achievable. But you aren't also going to be fluent in 10 languages, an expert computer programmer, a world-class guitarist, and a grandmaster in chess.
I'm alright with only being an expert in things I'm able to devote full-time efforts to. But I'd also like to be pretty good in other stuff. How can I take bits and pieces of time here and there to achieve that? That's what I'd like to see some research (formal or informal) on.