What usually happens is that the programmers think about the project long before starting to work on it. I have 3 ideas that at some point I'll start implementing, and right now I'm gathering bits and pieces of information for all three.

And when it comes the time to do it, the core functionality can be done really fast if you have good tools, since you are prepared for it.

What separates the good projects from the bad ones though are final touches and the features that are expected by the users - those weird business logic additions that aren't properly defined. These take an incredibly long time to do. Not to mention deployment and scaling which is always a fun ride.

And of course, there's always that intern/junior that has to work on something, and he's given the task of helping you, leaving a mess in any module he touches ... and then you have to clean-up the code, just to keep your sanity.