At times I get an idea about the topic I want to write. But then I realize I don't know enough about it to write something sensible about it. And I do want to make things properly so I don't give out disinformation. It's a nice motivation to learn something new. It's not like I'd have any lack of such things anyway, but it's just one more of those.
The problem is, I might have the idea just when I need to write. And in those situations I'm probably in a hurry. There is barely time to write something I know already. So there definitely isn't time to first go and learn something new and try to understand it well enough to be able to write about it.
I don't think it would be enough of a topic to write twice about it. First, when I get the idea, describing the problem and goal. And then later add in the solution via what I have learned. The former might need some additions to make it long enough. Perhaps writing about my assumptions there as well might help.
The most important thing is writing those ideas down so I can return to them at better time.