Reusing Animation Assets
The third factor that reduces the amount of development occurs after development has already begun. Now that there are actual scenes and characters to look at, you will find instances where you will have already drawn these frames. You can go back and reuse those keyframes.
It makes a lot of sense to have an inventory of assets. That inventory is a list of deliverables that can be checked against the storyboards, thereby making it easier to develop the game.