This is slightly more as an aide memoire than a post but Mark Carrigan has written a useful post on about academic blogging on the Post-Pandemic University blog, Academic blogging – both/and rather than either/or. The note towards discussing research that is already written or planned is the part that resonates.
I suspect that, like many people, I discuss ideas with colleagues and friends over coffee or similar. Sometimes these go somewhere, other times they sit as ideas. However, even if the abstract idea never goes anywhere, it will generally spark ideas and considerations that are worth discussing. Using the blog might be a way of discussing the work outside of a paper and to gain a sense of progress.
Recently, I have been remiss while I try and bring a disparate set of projects together into some coherency. Ideas swirl and, once the screamingly urgent deadlines have gone by, can begin to be discussed.