By the 62-hour mark, the Note 8 began showing a sudden and noticeable signs of burn-in, despite not having significant signs prior. The tester asked people to identify burned in parts of the screen while displaying a white image, and while they had no trouble identifying it on the Note 8, it was not visible to users on the iPhone X.
The test, first spotted by BGR, eventually ran for a whopping 510 hours, or more than 21 days —well beyond the amount of time that any smartphone OLED display would ever show a static image in normal daily usage.
In the end, the Galaxy Note 8 showed the worst signs of burn-in after the marathon test. The Galaxy S7 Edge, despite being a 2016 phone, performed admirably, but was still bested by the 2017 iPhone X.
After three weeks of displaying the same image on maximum brightness, all three handsets expectedly had potentially permanent signs of burn-in. But the tests also show that Apple's efforts to reduce the effects of OLED burn-in have paid off.