When it comes to one's own stories, I feel like there is a kind of "storyforming continuum".
On one end of the scale is when you have a very strong story idea, developed enough that the throughlines are recognizable. In this case there probably already is a storyform* even if you don't consciously know what it is, and your subconscious may resist you if you try to cram it into a different storyform. (I say may but I know mine would!) Generally what you want here is to find the storyform that represents the structure you've already got in mind. That storyform can still help you develop your idea further and write it, since even though your idea was complete enough to get down to one storyform, you may not have considered all the story points, and probably won't grasp one or two of your throughlines as well as the others.
* or a small subset of storyform variations, e.g. the same basic storyform with different Outcome.
On the far other end is something like the Story Embroidery exercises, where you start with a storyform and make a story from that. (YouTube videos are available for some of the DUG Story Embroideries, or here's an online example that we took pretty far: Story Assembly II)
In between would be things like your idea at the start of this thread, which might fit best in a certain OS Domain, and/or a certain Concern quadrant, but the rest may be wide open.