The absence of visible damage is not proof that nothing needs attention.
REFLECTION
REFLECTION
No visible damage means only that nothing has surfaced yet. Wear, fatigue, and drift all work below the level of appearance for a long time, which is why inspection exists and why appearance is such a poor guide. Waiting for something to look wrong means waiting until the process is well advanced.
Check things on a schedule rather than on the evidence of your eyes. The point of a scheduled look is to find what has not yet become visible.
What looks fine on the surface but has not been checked?
Free, with nothing to buy inside it.