I use my tiddlywiki for journaling, project management, as a personal CRM (what were the names of their kids again?), as generalized notes for studying topics I care about, and as a place for fiction writing. Each of these contexts have different lengths.
I sort of meditate on this question without worrying about it, if that makes sense.
A paragraph in a larger short story might get excised so I can work on it elsewhere and focus on it. Larger essays might end up with a bunch of these transclusions but, in the end, I can export them when I need them so the underlying structure doesn’t matter as much.
My morning brain dumps are usually around 300-500 words.
The things I think of as the “results” of what I’m thinking about that could turn into writing tend to be made up of smaller, “atomic” bits. One to three sentences, tops. That’s the goal, anyway. I’m not a strict zettelkasten adherent, but I think that’s what they tend to do, too.
In the end, I don’t know. Sometimes I think about it and break things up. Other things I leave alone. That’s a whole lot of words for “YMMV”, sorry.