A use case for keeping it on is that WiFi can be used to improve your phone's location accuracy ("GPS" services): https://en.m.wikipedia.org/wiki/Wi-Fi_position

A use case for keeping it on is that WiFi can be used to improve your phone's location accuracy ("GPS" services): https://en.m.wikipedia.org/wiki/Wi-Fi_positioning_system https://en.m.wikipedia.org/wiki/Wi-Fi_positioning_system It also significantly reduces the time to get a location, where satellites can take minutes to acquire (at least that was the case, back when I worked with GPS at that level)