The person who knows the routine needs a break that does not depend on staying available.

Being on call is not rest, however quiet the phone stays. If the whole system runs on one person’s knowledge, then every hour off is really an hour of waiting to be needed, and the mind never puts the thing down. That is why a caregiver can take an afternoon and come back no less tired than before. Genuine relief means someone else can handle what comes up without checking.

If you rely on one person’s knowledge, spend an hour learning it properly before their next break. Write down the parts only they know. Then let them go somewhere with the phone off and mean it.