Honestly? I don't know why everyone else isn't doing the same amount of work... My guess is that they have families and lives to concern themselves with as well, instead of dedicating themselves to one or two specific tasks. (Which isn't a bad thing, overall, but it will slow you down, as well as lower the speed of learning a given craft or skill.)
That isn't me saying "I'm da greatest" after all, I have a lot more to learn, and plenty of room to grow! (I've been reviewing the early Young Ancients series, for the next Dare book...Golly was some of that early stuff bad. And the typos... Sigh. Even at the point where it gets better, I still need work.)
The thing is, I get to practice these skills on a near constantly level, and see that progression, as well as go back and analyze what I'm doing for errors. That is mainly due to my freedom to work and come up with new things.
The stand alone books are valuable to me, however, since it lets me try and branch out, stretch my creativity and break into a new framework! The problem is that readership patterns are changing, thanks to the new Kindle model, so large works, including incredibly big compilations, are more valuable than standard sized books now.
If that changes, which it eventually will, then going all in that way could work against me. If I disregard it however, that too might be a point of potential failure.
So, my current plan is to try and do both. Series works, come up with new compilations of old series, and a variety of stand alone works, possibly of good size to work in the current system.
Also I think I want to spend a bit of time now doing rapidly changing worlds, as far as writing. I don't really want to go stale.