Not really a one-shot thing. More like you have one attempt to downgrade. If you fail and you are soft bricked, you can use recovery mode to fix it but you will no longer be able to downgrade (if Nintendo patches it ofc).
I mean, that's what i'm talking about.
Personal opinion I guess.
What would you rather?
1. if it fails, either high chance of brick or you try again.
2. Very low brick chance, but if it fails, you're stuffed.
Dunno. Worried that option 2 will never come around. Even KTM has some code to auto-retry when soft-bricking.