'Day-of coordination' is a bit of a misleading name — most of the real work happens in the two weeks before your event, not on the day itself.
In that window, your coordinator collects final headcounts, confirms arrival times with every vendor, builds a minute-by-minute run sheet, and identifies conflicts you'd never spot yourself — like your caterer and decorator both needing the same access window.
On the actual day, the job is to be the single point of contact so you and your family aren't fielding vendor questions during the ceremony. If a delivery is late or a vendor no-shows, that's a call your coordinator handles, not you.
The value isn't really about the day itself — it's that you get to actually experience your own event instead of managing it.