The custodial effectiveness audit should be performed during a period of normal business operations (although it need not be performed during business hours), when occupant loads and activities are anticipated to reflect normal levels and patterns. The auditors should not perform their inspection during the day, as custodial staff have no control over things like occupants leaving a mess at lunchtime. It makes more sense to audit relatively soon after the day's (or night's) cleaning is done so that you’re auditing the job done by the service provider rather than the messiness of the occupants.