One of the lessons I took from this project was to check your assumptions / know the context in which a part functions.  I didn't understand how the part fit into the entire saw assembly and assumed that I could make it longer for the sake of my design convenience.  A longer part allowed me to smoosh two assemblies together, optimizing air (and sawdust) flow through the part.  The first version of the part was - surprise, surprise - too long.  It hit the motor on top of the saw, effectively negating all the nice work I'd gone to, to make it fit well.  

I only revised the part once, but when given the opportunity, I decided to tune up a few minor details that bugged me, making me happier with the final product. 

Lesson: Look not just at the part you need to make, but how it fits into the entire assembly. Expect iteration, but don't sabotage yourself!  

Corollary: If you think it's perfect in V1.0, it probably ain't.