purchanceallus
It seems the reason they thought they were done counting is because a supervisor told the counters to go home, and said that they were done counting for the day.
Relevant part from the linked document (paragraph 8):
"Sometime after 10 o'clock p.m., the counting activity slowed. Shortly afterward, a younger lady with long braided but blond hair yelled out to all of them they should stop working and come back tomorrow (the next day, Wednesday November 4th) at 8:30 A.M.. Thereafter, all but 4 election employees left State Farm, leaving just the blond haired lady (who Michelle and I assumed was the supervisor), two older ladies and Regina Waller at the location. This lady had appeared through the night and Michelle and I believed her to be the supervisor."
I think that while it is possible the observers could have just stayed there until everyone left, it is likely that they believed what they were told -- that the counting would finish the next day.
At any rate, it is at best a bad look. I agree that it doesn't prove fraud or anything close. It does, however, look suspicious and IMHO warrants further investigation.