I think read reviews is not important... I'm learning on my own bads/bugs/errors...
Also sometimes when I'm so bored, I'm playing high-rated levels like "Devres" and "Another Dimension"...

And I think to make SP pack need lesser time than half of year... (I lost only 4-6 months in making fan-mission for game Thief 2 The Metal Age...and this mission got pretty high ratings from fan-players...)

I lost very much time in Ever Story I, but made a big bag with bull***t...
I think problem is not amount of time...There's just need to know JJ2 gameplay, high-rated fan-levels, and create new levels under "Just Do It!"

Also I think main point is: Inspire... When I'm inspired, I can loss less time and make good project (as i'm doing with new ctf lvl)

Well, And I think featured will come to me, if I'll just relax, sit down, and just launch JCS... Every new level will become much better than past... (sorry for crappy english, i hope you understood my point)