I feel that as long as the time-delay is long enough, the eye movement decreases frustration more than difficulty. For example, I spent 10 minutes (and I could have spent much longer) looking for the scroll in the teacherĀ“s house before I noticed LinkĀ“s eyes.
I canĀ“t remember how many times IĀ“ve solved a large puzzle several times over but not completed it because I missed a small part of it. Imagine trying to light a whole lot of torches: you run from the start to the finish, and by the time you get to the finish you presume the reason nothingĀ“s happening is because the earlier torches have gone out, but the fact is youĀ“ve missed one all along. ThatĀ“s the sort of thing that LinkĀ“s eyes can tell you. What they canĀ“t tell you is why you need to light the torches, or when you need to to turn the dungeon upside down, or how you need to defeat phantom gannon etc.