These threads announce a mod that will be released in a year or months from the thread. They may also ask for suggestions. I'm getting tired of these threads because some of them are never released or will never be released for many years.
If you make a thread here about one, it'll probably be moved or deleted.
I think @boxmein is right. There should be a link to github showing the work being done. If you dont have proof that your mod will be out within a few weeks to a month, don't announce it.
Yes, I think Github commits or some sort of proof would be best to show you're atleast producing something. Though it has to be something major, like 2 or 3 elements made or something. Not just one element and a new title.