when working for my previous operator flying a light twin piston we routinely did a full power check upon leaving the hangar in the morning, then shut down to collect our pax. This was so that the aircraft could be assessed as servicable keeping inconvenience to a minimum if otherwise. After that the checks would be reduced to engine checks with only a full runup being done every two to three sectors but a mag check always prior to departure. This was considered acceptable for a few reasons. Firstly our turn around times were short, rarely more than ten minutes shut down so the engines remained warm. More importantly the engineering standards on the aircraft were fantastic. At takeoff power there was never much out of sync on the engines and the engines always ran up at the same speed. It would easily be recognised if there was a power problem very early in the take off roll. As a point of reference the accumulated fleet hours are probably around 100,000 by now and have only ever had to carry out three inflight shutdowns.