Yeah, once you start getting more advanced in your maps you will need to learn how to change and line up faces, this will become important for adding non rendering faces (nodraw), in other words one block can have 6 different textures 1 on each face, it becomes most important when adding lights because the lights wont draw on these "nodraw" faces saving lots FPS and even more important if adding a high amount of Cubemaps... (ramble) eventually you will come to learn this on your own.
Most GunGame maps don't really need to worry to much about nodraw because they are small and have a low amount of block faces.