Nick Lappos had a jar of beans analogy for engine fatigue - your engine has a finite number of beans in its full jar when new (jar empty = TBO) - the more you use that engine up to (and possibly beyond) its published limits, the quicker you use up the beans and the sooner the removal/replacement/overhaul time arrives.
Most important is to keep your engines in good condition so that they do provide the required 5 min and 2.5 min power if you need it - compressor washes, Power Assurance Checks and close trend monitoring.