I generally shrug and tell that it's their call. They can schedule the 8 hour shutdown at their convenience or call me in the middle of the night during their busiest season and we'll start the clock running on their 1-2 week outage...and the estimate that I gave them won't be valid.
Sounds a lot like how most cinemas look at projector repairs.
I had one cinema, who was advised of an imminent failure of a key part (cost; $2,000); they chose to wait.
The breakdown happened with a full house (500+ people), on a Friday night, with one of the top grossing films of the year. They had to fly the part in on a charter jet, fly the tech in on another charter, refund all the paying customers, lost an additional 5 shows, and caused over $1,500 in damage to the film.
I was told by the asst. manager that it all came out to over $14,000!!
Some people never learn.
But of course, that wasn't potentially life threatening. But sadly as seen by quite a few posts here that cavalier attitude carries over into electrical equipment upkeep.