I think it'd be better to find out what songs they like, then teach them their favourites.
This is what I do. To an extent.
I devote half a lesson to what I think they need to know. Basic stuff, theory, good technique, some songs that use the lessons.
The rest is going through a song of their choice.
I think a good teacher (of something creative like guitar at least) needs to help their pupils become the guitarist that they want to be, not what you think they should be (save whatever lessons you have on good technique, making them not do things that might, y'know, give them tendonitis one day or if they're making it really hard on themselves, picking from the shoulded or something, and basic theory, chrods, cycle of keys, entry level scales and the like), and that it should be fun, and the best way to do that is give them the satisfaction of being able to play their favourite songs.
This applies many, many times over if the pupil is a child.
