Good analyses of the situation. Indeed, posts get invisible very quickly. Every new post come in the NEW channel for anybody to see when the surf to this channel, and quite a few Steemians do that, like I did and discovered this post. When the post get quickly some votes with some power behind it, the post gets higher up in the HOT channel; In this channel posts can keep kind-of-the-same position for some longer time, maybe an hour or two. After that only the Trending channel is available, but most post never get into this channel. The posts also gets into the HOME channels of the followers, but also here the post can quite quickly be undiscoverable depending on the number of posts getting into this channel and the behaviour of the HOME channel owner in scrolling looking for good posts. For what I've seen with my more than 200 posts, is very much the same behaviour as you describe.