I do it every day, I only calibrated the + on the track; besides that, I never run on a track. I only run on trails and roads.
yeah, but do you do it on *measured* roads and trails? My point is that if the only time you get to compare it to a measured distance is on a track, it's no surprise that it will seem accurate. If it were accurate over measured miles on the trails or roads, that would be a lot more impressive.