It doesn't top out below 144Hz. There are benefits with diminishing returns up to at least 1000Hz especially for sample-and-hold displays (like all modern LCD/OLED monitors). 240Hz looks noticeably smoother than 144Hz, and 360Hz looks noticeably smoother than 240Hz. Past that it's probably pretty hard to tell unless you know what to look for, but there are a few specific effects that continue to be reduced. https://blurbusters.com/blur-busters-law-amazing-journey-to-future-1000hz-displays-with-blurfree-sample-and-hold/