For a question, a room, a private supper. We answer most messages the same evening; everything else the next morning, with breakfast.
For quick questions in transit. Read in the office, replied to in twenty minutes during the day.
For something that needs a voice. In the office between 08:00 and 22:00. After that, the bell.
For longer notes — a wedding plan, a special diet, a writers' week. Read with morning coffee, replied to by lunch.