Many businesses like yours authorise their onsite supervisors to conduct the final quality control inspections. This is not best practice for many reasons.
First of all, the onsite supervision has too much invested to be an unbiased inspector. They will be tempted to take into account the realities they have experienced. Such realities may include a late start, absenteeism, emergencies (real and not so real) as well as equipment malfunctions and other excuses. With such information in their head, they will tend to grade the work on a sliding scale to allow for these excuses.
They also are emotionally engaged with their staff and may be reluctant to make work for a worker who did them a favor by staying late or covering other tasks.
If they have been trained to a standard, providing the correct equipment and allowed sufficient time to perform the prescribed tasks, they should inspect their own work and correct any deficiencies they find. However, most staff to do not look at their own work with unbiased eyes. We are all good at justifying our own actions.
Inspections should be conducted on different levels. If staff are using the same inspection form and grading system as the onsite supervisor they can identify areas missed and make note of the corrections. The onsite supervisor should accompany them on their self-inspections often enough to verify that they are being performed correctly. This one act will give the onsite supervisor insights into how effective the training has been as well as adjusting training for future staff.
Some of you will react to the preceding suggestion noting that it will involve too much time and effort. This is where an Eye On Detail can provide a service that management can act on. New eyes see new problems. For a small fee it would be a tremendous investment in accountability and reduced customer complaints.
Your comments and questions are important. I hope to hear from you soon. Until then, keep it clean…