The calmest events are not the ones with the fewest problems. They are the ones where everyone knew who to ask, what was next, and who was calling it. Day-of coordination is a system you set up in advance, not energy you summon on the day.
One show caller
Someone has to be the single voice that calls cues: lights, next speaker, go to break. It does not matter if that person also does ten other things in planning, on the day they call the show and others execute. Two people calling cues is how a transition gets fired twice or not at all.
One live run of show, visible to all
The plan you built only helps if it is in the room and current. A live run of show shows the current cue with a running clock and what is queued next, so the MC, AV and catering are all reading the same screen instead of asking. Event70 switches your cue sheet into a live mode that does exactly this when the doors open.
Decide how you will talk
Agree the comms channel before doors: radios for a big production, a single group thread for a smaller one. Set the etiquette too, short messages, names on requests, and one channel kept clear for the show caller. A chaotic comms channel is its own emergency.
Protect the buffers
You built buffer time into the run of show for a reason. When you are running early, hold to the clock rather than starting the next thing, because guests time their return to breaks. When you are running late, take it out of transitions and buffers, never out of the headline content people came for.
Build the cue sheet in the run of show builder, then run it live on the day. Start free and your first event is on us.