Any developer or implementer can create something. The successful ones are the ones that take the existing formula and use it for their own use. Most of the design and leg work has already been done for you. There's really no need to re-invent the wheel.
Another important reason why you should try to find similar existing functions is the design aspects of NAV. When the users are using the system and using the function that you will masterfully create, the trick is not to remind them that this function was "bolted" on. Remember what we say about the consistency in the user design; it absolutely needs to be consistent to speed up training and user adoption.
This chapter goes over how to dig into existing functions and features you would like to replicate into your project. Once you find these similar functions, you will be able to model the solution after what's already been created.