Learning to ski is certainly a particularly strong example of a case where you're likely to have a lot of false positives.

But, honestly, even with something like hiking, tripping over a tree root or something like that isn't exactly rare. I've taken a ton of spills over the years and fortunately nothing worse than some minor bloodshed or maybe a twisted something was involved. (And the one time it was something more serious I didn't actually fall but did have a serious bone break.)

I've been on the fence whether I ought to enable the feature on my watch.