The OLEDs have a finite lifespan.
Uneven usage creates the illusion of burn-in.
It's not burn-in, but rather aging; OLEDs grow dimmer as they age. CRT phosphors do not unless burned.
The goal is to create an even pattern.
Black is good...
Burn-in only happens on CRTs, it is the phosphors being physically burned be the electron beam.
This can happen rapidly if the brightness is high and it's a small none moving dot etc.
This is actual physical damage from abuse rather than normal wear. The power density of electron beam wasn't design to be focus on one spot continuously; the phosphors can't dissipate the heat.
OLEDs grow dimming as they age; CRT phosphors do not unless burned. In fact a CRT can be reuse by replacing the gun assembly.
For OLEDs to maximize there life keep brightness 50% or below.
>Keep image moving; avoid static images that stay in one place.
Blue light has higher energy and causes faster display aging.
If you choose brighter colors it will degrade the screen fasting than faint ones ie more black mixed in.
Samsung automatically moves the clock about the lock screen to prevent uneven wear.