Ours stay on all the time. Our provider has specifically said to leave it on and only switch it off if the modem needs rebooting.
I hadn't heard about the health risks but y'know, just about everything carries a health risk. Just being alive comes with a 100% risk of death one day..... so I don't worry too much about such things.
I didn't know there were reported health risks...although I'm not surprised! Our wifi is in the study - which is outside of the house. I leave it on all the time as it connects to the inside computer (In my partner's study) and our phone's connect to the wifi.