Also in lycoming's service instruction 1009 states engines not reaching TBO hours within 12 years should be Overhauled regardless of hours run
Very few private ops implement this 12 year limit.
This limit merely serves as a liability limitation for the benefit of the engine manufacturer
For example Lycoming have just stuck a 12 year limit (which has becone an AD and is thus mandatory) on about 6000 of their crankshafts...