I do not normally post but Sandbanks post has got me going,
A test flight for every mainetnance action is just impossible, there would only be empty aircraft flying ! A test flight is normally only required if there have been changes to flying control systems. For engine work (Including replacement) an engine ground run is performed as per the manufacturers instructions, with a level based on the work performed.
Any maintenance tasks performed to aircraft 'critical' systems require a duplicate inspection of the work completed by two independent Engineers
Just my thoughts.