[FridayoLeary]

>Because the watch performed better on earlier versions of watchOS, and even my iPhone 4S was better at tracking, I think the issue is software.

>The measurement errors are so bad, that they overshadow performance differences between runs, and during runs. At the same time Apple keeps adding more and more incorrect stats and graphs, building on top of a shaky foundation. The kilometer splits measured in seconds imply more accuracy than is delivered.

This.