I also have this dilemma (although I haven't written in a while due to time constraints). Depends on the subject matter I suppose ... if you are able to hold the reader's attention with interesting and captivating writing, a long post is great. For some general info on Steemit and for assistance in all things to do with this platform, check out @davemccoy. I also enjoy certain autobiographical writing, and a recent piece on Elon Musk which was very long, held my attention throughout. It was written by a seasoned journalist, @neilstrauss, really good. I enjoy your writing, try a longer one ...