Apple Watch is USELESS at recording 'Outdoor Walk' as exercise. Use 'Other' instead.

I bought an Apple Watch in December intending to replace (eventually) my Fitbit Ionic as an exercise monitor. Initially I set up my everyday brisk walk (up and down 3 hills) as 'Outdoor Walk' on my Watch and was appalled to see that my 60+ minute walk recorded (at most) 15 minutes of exercise. As a control, I wore my Fitbit on my left arm, and my Watch (set up correctly) on my right arm. For Apple's 15 minutes, Fitbit recorded 67 'Active Minutes'. Having read some of the online forums on this problem, I set up my Watch to record 'Other' exercise instead - hey presto! Both the Watch and the Fitbit recorded the same 60+ minutes of exercise or 'active minutes' (Fitbit). The Fitbit has the same data for its algorithm, as it has age, weight, height, resting heart rate etc - and measures arm motion to identify steps/exercise. The Watch appears to use none of this information for 'Outdoor Walk', relying entirely on GPS to measure distance/speed. Indeed, if it is not in Airplane Mode, the Watch completely screws that up too, as it bounces off Mobile phone masts for location information instead of using GPS, as is obvious from the crazy zig-zag that it recorded for my first 'Outdoor Walk' which tracked nothing llike the actual route! Basically, the Apple Watch, as a monitor of exercise using the 'Outdoor Walk' category, is not fit for purpose. I'll stick with my Fitbit Ionic & just use my Apple Watch as an expensive timekeeper.