That's a very interesting experience I'm going through right now: I'm still somewhere in the middle of creating Level 12 - "Welcome to Paradise". You could say that within a few days I made some very nice progress (I'm not working full days every day ... so after a month, I can still say "within a few days" ;-) ). I am spending significantly less time than I wish on developing Traces of Illumination right now - but that's another (much too long) story.
Anyways, many of the things I had planned for this level worked out pretty well, some even better than I had imagined it - and I even came up with completely new ideas for this level. But I also get my "lessons" in 3D modelling.
Warning: This could be a bit of a spoiler - so only read on if you don't mind reducing the surprise-effect a bit when you finally get there after completing the previous 11 levels. ;-)
Level 12 is completely different from all the levels before. Which I think makes sense because it's the "last" level (actually, it just puts you into another "cycle" - pun intended ... no, not *that* pun - the one that has to do with bicycles and repetition of the "same thing" but in a different, well, Tracer ;-) ... well, after 12 cycles which means 12 Tracers, getting there is a little different ... but that's obvious because that's the real "end" of the game).
One thing I'm creating for level 12 is a cave. And ... I've switched to a new 3d modelling tool (Modo). While "creating a cave" may sound simple, it's not. Actually, this cave is what I've spent 80% of the time I spent on this level with so far.
And, I guess I made every possible mistake one can make when modelling a cave.
That's why I'm learning a lot right now. It's "learning it the hard way" because sometimes "weird stuff" happens (like verts being "displaced" from their edges). Then I wonder what's going on for a while, try this, try that ... until I realize that I made a mistake much earlier in the process. And the bad news is that sometimes this means "go back and start over".
In this particular case: I created a displacement map for the cave and did a lot of "sculpting" - but I did so before cutting out the holes that act as entrance to the cave. Aside of probably breaking my UV mapping in the process of "digging" those holes (which will render my displacement map and "cave painting" useless) - trying to do precision modelling on a mesh which has a displacement map on it is ... well ... "confusing".
I guess in the end I'm simply currently experiencing the difference between being a professional in one field (the programming part) and being an amateur in another field (3D modelling).