Measuring service does not in itself improve service, but development activities planned on the basis of measurement results. Mystery Shopping should be followed by development activities, either for the department or for the company as a whole.
If the aim is to include the results of Mystery Shopping as a single measure in the employee bonus system, it would be sensible for each employee to be subjected to several tests nominally during the year to measure his or her level. If the goal is to measure the average level of departments on a random basis, then depending on the number of employees, budget opportunities and the impact of departments on business results, a service audit is useful either monthly or quarterly. Certain departments are certainly more critical than others. In our practice, we have partners with monthly Mystery Shopping cooperation, as well as those who do, for example, 2 large-scale waves in a year.