I hope this isn't too far a diversion:
In the CRT days, I'd pass through offices in the early morning when the computers were still off, but you could see the menu's of the application most often used on the display as an image negative.
I had two SOYO LCD monitors I retired just last year which began exhibiting a similar burn in effect at the top where menu's are typically shown, but that was only visible when the monitors were in use, showing other images (diffferent from the menu often there). Those SOYO's were probably 7 years old (I can't be sure, they were used) - 4/3 aspect ratio.
Burn in is real on LCD panels, but they were older tech. It takes a long while.
Yet, I'm at my machine for way too long every day, so they're seldom off. Even if I'm not in the chair I'm probably running some task that I'll check on every now and then at odd intervals, so powering down doesn't happen often.
I'm not sure how resistant modern monitors are to burn in, and LED should outlast CCFL lighting (and their inverters).
Yet, I often do think to myself, "I keep this things on a awful lot of the time"...