There are two types of “roving sub” assignments. I have just completed one “fast” roving assignment this month and have four more unknown types lined up for Feb. and March.
Since I never know who will be running the roving schedule, I will ask the interviewer if they want me to hold strictly to the schedule (slow) or to send the next teacher as soon as the previous returning teacher releases me (fast).
The health insurance auditors usually want to be done as quickly as possible (fast) whereas the twice yearly principal/teacher evaluations tend to plod along at the preset, scheduled (slow) pace.
If I have a choice, I prefer the fast roving schedule. Even just a few minutes sliced off each early ended interview adds time to the front end of my lunch period and subtracts time off my end of day release.
In either case, I’ve never had a school require me to stay beyond the end of the last interview.