I don't know why this works, but it works on these parameters:
Insane difficulty
60min days
12 hour night cycle.
Game Stage around 40 right now.
The issue is at this low stage the hordes mop-up around 0100 to 0200 hours, maybe 0300 hours. But Night goes till 10:00 hours in the 12 hour cycle so it seems. If you log-out of the single player and log-back-in to the single player, you get another horde that then ends at 10:00 hours.
Not sure if that's a glitch just specific to those game settings?
Insane difficulty
60min days
12 hour night cycle.
Game Stage around 40 right now.
The issue is at this low stage the hordes mop-up around 0100 to 0200 hours, maybe 0300 hours. But Night goes till 10:00 hours in the 12 hour cycle so it seems. If you log-out of the single player and log-back-in to the single player, you get another horde that then ends at 10:00 hours.
Not sure if that's a glitch just specific to those game settings?