What a commercial programme is for
A commercial contract is not a residential visit repeated more often. It exists to do two things at once: keep activity down, and produce evidence that the site is managed. An auditor, a landlord or a regulator is assessing the second as much as the first, and a site with low activity and no records is in a weaker position than one with a documented response to a problem it found early.
So the shape is survey, then a numbered device plan, then scheduled visits with monitoring recorded at each, then review. The monitoring is what turns sightings into a trend, and a trend is what lets an interval be shortened where it matters and stretched where it does not.

