FWIW, in the hallway tutorial, I would just clone and stretch bits of one of the rooms to make the hallway. For example to make the hallway floor, I would clone one of the room floors, and drag it to position, and side stretch it to fit.
Of course, that is purely a matter of personal preference.
The nice thing about cloning is it saves texturing. Cloning and sidestretching a brush is roughly the same number of operations as selecting, deselecting and creating a new brush. If you do use clone, you should have texture lock off. In general, I do all construction with tex lock off, except where specific allignments are required. Having most of the textures on their default allignment makes editing easier. Also, once you get on to structural and detail, cloning your previous brush preserves that for you.
Nice to see ‘first room’ tutes that don’t use hollow or CSG subtract 