And even if you are a game programmer, it isn't really necessary to know the underlying implementation of 3d code.
It might be useful but I believe that it would be a bit smarter to pick an engine and start making tons and tons of demos. Everybody loves to see demos, including the companies that are going to hire you in the future.
Knowing general 3d programming is pretty much a fundamental aspect of programming 3d games.
Demos are boring, if you really want to learn to code properly and not be a demo kiddie then write a game, any game to the end. You will learn more writing space invaders from start to finish than writing a demo of a sphere with per pixel lighting rotating in space.
