Slaton and the others were skeptical of the shield Brenna put up at first. They couldn’t see it. They couldn’t feel it. They only had her word about something she couldn’t see or feel either. She then asked them what really made sense in anything they were experiencing: supernatural mark, immortal demon, prophecies, connections, and strange powers. That was enough to convince them.
The shield was the extra protection they needed when they were not on patrol. It allowed them to eat together and rest for a few moments, but neither Layford nor Miakoda felt comfortable not being on patrol. They trusted Brenna, but seeing the perimeter themselves would make them feel better.
They still carefully chose the campsites. They could not assume Jolon couldn’t see them. Assuming had hurt them in the past and could kill them now. It was better safe than sorry.