I don’t have hard stats to back this up, but with the new watchOS 6 it recently improved quite a bit for me, also on Watch Series 4. It’s particularly improved with workouts, though I would still love to have a feature that can “Undo” pausing a workout or vice versa, undo a workout that ran 20 hours longer than it was supposed to. Don’t get me wrong, great watch, great improvements, just... not perfect. Also, being able to track my activity between sleeping periods instead of only midnight to midnight would also be nice to have.