Personally I don't look at the ATIS or METAR so much as I do at MY wing. I don't base my decision on what everyone else is doing - only what is on my aircraft. If it is only very light snow and it is melting on contact and the temp is 3 or 4 degrees chances are I'm not deicing but every situation is different. I also consider the current and expected operational status of the airport and location of the deicing pads to determine whether I apply type 2 or 4 fluids.