Ok. 5 minutes. The point is clearly there’s route changes happening globally already. It should not be that much extra work to add like 10% more route changes (again - you’d batch the new route advertisements in one cohort rather than updating each individual route back and forth).

And stuck routes are a problem but not one this would make worse since those routes would get stuck from normal changes anyway.

The propagation problem isn’t real because clearly most route advertisements that handle most of the traffic actually happen quickly. You shouldn’t care about the long tail - you want to minimize the risk of your new route. The old route being present isn’t a problem and the new route disappearing back to the old also shouldn’t be a problem UNLESS the new route was buggy in which case you wanted to rollback anyway.

TLDR: these don’t feel like risks unique to advertising and then undoing it given the route publishing already has to be handled anyway AND cloudflare is a major Tier 1 ISP and handles a good chunk of the entire internet’s traffic. This isn’t about a strategy for some random tier 2/3 ISP.