Avarris was brought in at the optimal balance time between "get some feel for the patient under the previous semi-equilibrium state being maintained, before starting complicated new processes" and "preserve stamina for operating the new protocol".  She's still maintaining essentially Merrin's equilibrium, and isn't making large mistakes that Merrin can spot about that if Merrin is monitoring at this remove.

Avarris was brought in at the optimal balance time between "get some feel for the patient under the previous semi-equilibrium state being maintained, before starting complicated new processes" and "preserve stamina for operating the new protocol".  She's still maintaining essentially Merrin's equilibrium, and isn't making large mistakes that Merrin can spot while monitoring at this remove.