What so often happens is you make a plan like this, then business priorities change/things took longer than expected/people leave or join and then you wish you never started...
The absolute highlight of my work is when I get a new projected 'scaffolded' (bad choice of words, but I was using it before it became a buzzword)
You know when you get to the point your data structures just make working on the code a breeze, when your library functions provide all the right low pieces to whip up new features quickly and easily with names and functionality that actually fit the domain... Basically, when all the pieces 'gel' :-D