Power Cycling question

I have a newer dual band wireless gateway that I'm leasing from Comcast. I heard mixed opinions on this subject before so I wanna ask it here;  Do I ever have to power cycle it, meaning to unplug it from the wall wait 30 seconds and plug it back in.  Some people say you only gotta do it when something is not working right, and some say you gotta do it every week even if everything is OK, what do you guys think? 

Also does anyone know if there is a saparate phone number for XFI support besides 1800 Comcast?