In many populated areas all is needed is WiFi to get 50m accuracy of your location. If there's no WiFi, a guess will be made, sometimes the guess isn't far off, sometimes it is.
At home, on my desktop, I have a wired connection to my router and out by ADSL. Location sharing is generally several miles off because that's where the DSLAM is. If I'm using my laptop at home, the WiFi is connected to my own router, which again, goes out the phone lines. The only time I'm likely to get more accurate location data from WiFi is when I'm on the road and using my phone. Of course, if I'm looking for a nearby gas station, a few miles isn't going to make much of a difference.