In order not to seem suspicious, the small groups wander around outside the sect to have small talks, eat snacks, clean the front yard and backyard, and all those normal activities.
But the small groups were all scattered around the sect, so they would know if anything suspicious happened outside.
The inner sect groups were assigned to guard each room inside the sect.
They would pretend to clean the room while spying some enemies' movement through the window.
Because there were so many disciples, the rest of the disciples who weren't on guard duty, took rest and ate, and also studied like usual.
There were two guarding shifts, morning till afternoon and afternoon till morning again.
Until noon, nothing suspicious happened.
But then, it's understandable. When the previous attack happened, it happened at midnight.
The disciples were told to stay cautious even when they were sleeping at night until midnight.
