The other day I was tracking my run on the FitBit app on my phone when I realised it wasn't showing on my watch. So at a specific point on the run I started the tracking on my watch too. For the following 6 or 7 km, depending on whether you trust my phone or my watch they proceeded to record my distance and speed differently. My Blaze relies on my phone for GPS tracking. My watch was on one hand and my phone in the other. So why was there such a difference in what they recorded?