The value of a classical education is in the laying of a foundation for your work to follow. One learns joinery in order to learn accuracy plus patience and the myriad ways there are to build. For instance, there are a dozen or more ways to build a box, but each situation requires an evaluation and then a decision. Your decision on joinery will depend upon factors like your knowledge or skill, the available tooling options, economy or speed, enjoyment, and finally how late the project is. [If it’s for a client or a birthday, it is almost guaranteed to be late.]
If you take the time to build your skills in a variety of approaches, then you can choose a joint for example that fits all the requirements of the situation. A nailed butt joint might be perfect when you’re in a hurry or the piece is not precious. It might be completely inappropriate for a shrine to your sainted mother. On the other hand, if you’re building mom a present and her birthday is rapidly approaching then hand cutting dovetails might take more time than you have. Splined miter joints are just as pretty but faster. Both work for the job and lend their own signature to the work.
-- Gary Rogowski...follow my wit and wisdom on twitter @garyrogowski