Flyboy,
OH, I missed that part. If the student is doing all the takeoffs, landings, etc, then yes, get them familiar with emergency procedures and cut that cord.

I gotta say, though, the 15min of holding the trainer switch after takeoff and before landing does take a toll .

Checklst,
Yeah, I agree with that. There are some instructors at my field who take over very quickly. I've taken to warning my students that I won't take over unless I think I have no choice, I expect them to keep flying and trying to save it, no matter what is going on, until I decide it's in danger of getting broken, hurting someone, or going over a no-fly zone (too far, I'm laxish with some of the boundries early on (don't tell anyone that ))