The R22 Maintenance Manual shows that if a visual inspection shows no damage, internat components (gearboxes, driveline, rotor hubs) will not need further inspections. Only when external damage is found, may you need to more thoroughly inspect and/or replace components. My experience with flight school operations in R22's, including full-downs, hover autos, running landings etc. have shown this to be completely correct.
Overspeeds are a different story altogether, of course.