It was private lessons, so no conflict with teaching others. In fact, he wanted me to join a small group class he taught for only folks who held rank (BB+) in some art already. (I couldn't join that because I was teaching at the same time.)
I was impatient - that's a character trait of mine. But what brings my impatience to the fore is when there doesn't seem to be a reason for not moving ahead. In this case, the instructor didn't have anything to correct, except that I should be doing the beginner's movement. What I mean by that is he didn't say, "You're not using proper technique - let's stick to the beginner movement and get that fixed." He said something like, "I know you're used to using smaller movements, but we have to practice the beginner movement for a long time before we can move to the advanced movement. The masters use small movements like you're working with, but that's because they're the masters and spent many years doing the beginner movements."
To me, that lacks any explanation of a reason to use that bigger movement, other than that it's supposed to be necessary. If he'd shown me some fundamental mistake I was making, I'd have happily done the beginner movement until that mistake was cured. There were places I didn't really understand the principles, and those places I gladly stuck to the beginner movement (or the closest approximation I could manage - like any beginner). And there were things my habits made difficult to do "properly" (using the technique as he was showing it), so I was happy to do those in beginner mode. But when there's no error pointed out, just an expectation of an amount of time that should be spent doing it exaggerated, my mind rebels.