I am not sure it has anything to do with whether your content is long or short. Others are also questioning their following. I know mine dropped but that was due to the fact I blocked many who weren't members and some clap and runners. I notice people I follow and read a lot aren't showing up consistently. I have to seek them out by looking them up despite I follow them. Sometimes they do show but doesn't seem consistent. Your experiments are good and will be interesting to see your future findings. Interestingly better stories I wrote didn't do as well as one's I thought would perform poorly. The one I published yesterday you interacted with, did surprisingly better than others before that I published recently.