From what I know a crt before having burn in, it would take about 12 months about 24 hours a day, on a static image, which is the case of airports at the time when the crt was used, I have a panasonic plasma that could burn in less than a month... ( they corrected this with an ingenious system, which shifts the image one pixel h/v per second so less risk, samsung and panasonic (ORBITER function) are done on plasma tv for example)
With a static image, the lcd are placed between the crt and the plasma
Burn in
Crt>lcd>plasma
In black video quality color video response time?
Crt>plasma>lcd
Modern plasmas have better phosphors that are less likely to "burn" in the first place. They also include features designed to lessen the chance for image persistence or remove it if it occurs. An ORBITER function moves the image around the screen by a few pixels. Hardly noticeable, but it minimizes some aspects of burn-in. Full white or rapidly changing colored patterns excite the phosphors evenly, greatly reducing the time it takes to remove the effects of image persistence.
LCD fanboys cry foul that these features are an admission by plasma TV manufacturers of a performance problem. To them, I say, what do you think
120 Hz, 240 Hz, and higher refresh rates are? They're an explicit attempt to "fix" the motion blur problem inherent in all LCDs. There's no such thing as a perfect display, folks; you've got to take some good with the bad.
https://www.cnet.com/forums/discussions/so-crt-s-can-burn-in-too-232218/