That makes a lot of sense. If it's sustainable, you're adapting. If it's not sustainable, you're not adapting.
I still wonder how long I'm supposed to wait before looking away so it doesn't doesn't get awkward. Staring too long, then yelling "I win!" when the other person breaks eye contact doesn't quite seem appropriate.
From what I once read, although it's in no way a scientifical fact, staring for 5 seconds informs that you're either sexually interested or angry/willing to hurt a person, while less than 2 seconds is lying/being weak. In the end, I normally set on 3 seconds.