If you're a half good instructor - at anything - you'll agree that you always learn more when you teach than when you are in the learner slot. Here's a vid of a young guy doing a training jump with me in February. My fall rate was a little faster than him, and our unlinked exit meant that he spent a while trying to dive to me. He'd come in hot - I'd duck, he'd come at me again and I'd duck. Eventually we caught up. Time again, I would've worn a more baggy jumpsuit - giving me the fall rate range to correct for him and he'd not have found the dive so tricky. I guess a student fresh off his A license tables who hasn't jumped for a few weeks could've used a little more help.
But this illustrates my point. A learning - and even an assessment - experience is a two way street. It depends on both the instructor and the learner. Happy endings here - Steve and myself blasted the jump the other day and we're both all the better for the whole experience.
It's the dual role of the teacher, in many cases. One has to turn from cheerleader to judge in an instant. The more mature students get that. The guy who's joking around with you tonight has to put his "judge" hat on the next day and mark your paper. But in the long run we're all the better for it.