I never propsed that teaching should magically add new experience.
I only suggest that while practicing improves your skills, praticing while overseen by a good teacher improves them much faster.
But it requires personal attention of the teacher, it is not free for him.
This makes it viable to be apprentice hunter for example - if you go out two, you can carry more furs, which would make the hunting more profitable for the master, and you will progress faster as an apprentice than you would on your own.
Teaching several people at once should only be possible when they are much less skilled than the teacher and the teacher has some teaching experience.
Teaching new members of a guild (in return for them to join the guild\'s cause) is the same as teaching random strangers for money or some other services, or even for free.