Well, I'll admit, I don't think any of Zelretch's students even started on the magic that would allow them to move between parallel worlds, so I can't say if there's any significance to the fact that we haven't gone insane or not. As much as it pains me to admit it, there's not much else I can say about it-Zelretch has a few objects that make use of it, but for obvious reasons he's not making how they operate public, and since he's the only one who has an extensive knowledge of it... well, you can see how it would get complicated.