Actually, it seems to me there are 2 ways to go. Yours are kind of in between the two extremes.
If you write a complicated and elaborate story, that makes it a better piece of literature on its own accord, but it also makes it less inviting to others to add their own chapters onto the end of it. It's not an invitation to do so, you're expected to read it and wait for the original author to write more. And if you do do the needed research and consideration to make a worthy addition, the author of the previous chapters is still probably going to hate your guts for what you did and make an enemy out of you (I wouldn't, you can write onto my long chapters). For instance, I saw a submission by this person named nothingsp, but which also had a user named chompy writing chapters, and then nothingsp would write after chompy's chapter. So I thought this was an invitation for anyone to contribute. So I familiarized myself with one of their running story's established facts, I made my contribution and what did they do? They didn't continue my contribution, they overtly rejected it, one of them immediately rated it a 1 and wrote their own chapters around it, not continuing from it. Or it was the 1-attacker who has been stalking almost all my chapters and hitting them with 1's with multiple accounts as soon as I submit them (which is why all my submissions have ratings on par with the ones where they can barely write English). I don't know.
But if you have something that's just a few sentences, that's just a template inviting others to write real chapters starting from there, and if you have a long and detailed story, that also makes it a lot of work for someone else to write onto it in addition to the strong likelihood the original author will be furious. Either way is a way to go.
