Does anyone know how often NAV traffic updates itself? ...or where they get their info from? Mine always seems to be out of sync with current conditions. (Seattle area)

Kinda funny and sad in a way because the local radio stations in Sacramento must get their info from the same source. I'll be driving and they will report an accident with 2 lanes blocked and I will be in the exact spot they are reporting it and there is nothing at all around. I think they all get their data from the Highway Patrol and news feeds probably.