Yo Dave. Hope you're enjoying an extended weekend.
I understand the sentement.
However, I disagree. And I have a LOT of respect for the folk who do weddings well (you know who you are!).
My problem with your realization is that, sure, it's not big deal for you. You just lost a job. You'll get more. But the real deal is that the married couple lost a memory. Or, rather, the preservation of that blessed event.
For me, I can take the stress of a lot of things ( I don't do weddings for the reason your mentioned, though - too much stress - - and for the reasong i'm hinging at here). But I refuse to be the reason someone has an unhappy memory about something that should be purely joyous. If I were to get married and someone offered me a refund on a botched job, that wouldn't cut it - for me.
Now, you phylosophy about, "Just stop and breath" is GREAT when you have control. Now, there's nothing that can stop you. You're the director. Make them do it again, get another shot, cut that one out, etc. I've even worked with some low-grade "major talent" and wasn't intimidated by them because of your phylosophy; just take it one step at a time and breath. Everyone's there for the same reason - to get a good result.
The one thing I would add to your phylosophy above is this: you know your job, you're hired because you've done it well before. There's very little different from this job (the wedding) and your last - except that a lot more is riding on this one (live event - one-time shot). Still, remember - you know your job. You're good at it. That's why you're there. Take it easy, take it slow and do what you do so well.
Anyway, just my half-pence worth.