Eventually I opted for a generic topic and a specific post.
My rationale was that there’s one subject for the whole topic so this should be generic. However the posts are sequential so it doesn’t make much difference to have one post or break it into two.
Does that work for everyone, or do you have other preferences?
(And chosing the right category is confusing on the desktop when a subcategory of a less obvious category would be the best choice. It’s clearer on the mobile version.)
I’m not sure we’ll be able to come up with a single rule here as I think it largely depends on what you’d like to get out of a discussion and what it’s about. That said, working out some conventions would be a good idea to encourage consistency of approach - as you say, etiquette.
Your approach to the Restart Radio ideas discussion makes sense to me given it’s a broad, ongoing topic - it’s a clear, accessible title that sets accurate expectations as to the content. Your first post then briefly explains the thread and presents an idea: a great way to bring people in.
I suspect as more people begin posting, we’ll see example of discussions that’ll need to work differently (e.g. if someone asks for advice around a specific element of repair).
tl;dr: that approach works for me, but I suspect it won’t apply to every discussion in future