Attach the preference to the occasion
For Saturday lunch, “Keep the dressing on the side for Pat” is enough to prepare the table. After lunch, remove the note from the standing menu. If Pat asks for the same arrangement for every visit, agree on that wording together. Add the visit date and the immediate instruction. Leave the reason out unless the guest explicitly wants it recorded and it matters to the arrangement.
Ask the smallest useful question
“For Saturday, would you like the dressing served separately?” is easier to answer than a request for a complete profile. Record the answer as given. If it affects preparation in a more important way than taste, ask the guest directly for their own instructions; do not infer requirements from a casual preference.
Review after the visit
Keep a standing instruction only when the guest asked you to remember it and the intended audience is clear. Otherwise retire the one-off entry with the event. Before the next visit, ask whether the arrangement still works. This prevents a single request from becoming a permanent description of someone.