Jet engine failures in either case are rare, so the specific operational limitation seem to work out...in part 135/121 maintenance is progressive...91 subpart K it is based on a more absolute approach...and they seem to both work
turbine creep is proportional to centrifugal forces and operating temps...and I believe that that factor is the biggest pain regarding turbines
perhaps and A&P or AMT could add based on personal direct observation...of engine conditions