It is a bit hard to evaluate overall metrics on a number of short vs long posts. Obviously there are more short posts. I bet a good number of the short posts are from Actifit.

I try to add substance to my Actifit posts, but I don't have time to do that every time, but I still want to track my steps on blockchain, the only way to do that in the Actifit application is to make a post every day and some of those end up short and I think that is why Actifit posts got a reputation for being "shit posts" 😀

But it totally makes sense that shorter posts earn a lot less. In my experience posts with 600+ words earn good rewards so 600 to 1000 words is probably the real sweet spot in terms of rewards for the effort.