Here is a situation we are worried about when we see a short cutoff:

In that situation, should you sell seats to people who come to the door or not?

If you cut off online sales two hours before curtain, you can print out the [rsvns] report a minute or two after cutoff. If the server goes down around then, or you lose connectivity, the situation will almost always be remedied within less than half an hour. During that time, no online tickets can have been sold, so you are free to sell whatever seats you know you have left.