iPhone X touch layer runs at 120Hz
Interesting bonus here. Capturing input data at every 8ms rather than 16.6ms allows you to start rendering the next frame in time for the next 16ms frame update, where if they were both at the same rate, you'd have to wait for the next refresh. So if the whole SoC is fast enough (and it likely is, if they did this), by having input data twice as fast as the screen refresh, you could potentially shave off 16.6ms of screen response time by drawing at the next 16ms refresh instead of another one down from when touch was sampled.
Confirmation:
https://developer.apple.com/library/content/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Displays/Displays.html#//apple_ref/doc/uid/TP40013599-CH108-SW5
Confirmation:
https://developer.apple.com/library/content/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/Displays/Displays.html#//apple_ref/doc/uid/TP40013599-CH108-SW5