I used to totally scrap a project, now I only scrap components. As I build experience, this happens less and less.
I had integrated Lua several years back - it took some tweaking (generally following what Lucas Arts did), but I sort of gave up on Lua. I didn't care for the general syntax and lack of experts. I'm seriously thinking about bringing in Python though. My init code is done through XML, though I'd like to perform some math, variable sets, and loops, and I don't think hammering XML into a pseudo scripting language is the way to go.