Better to write structure or story first?

I've written scripts with a loose structure in mind, but I just write and let the story go where IT wants to go.

But I've read that others plan everything out, like to a formula, writing the scene headings and filling the scenes in at a later stage with dialogue.

Personally, from a creative point of view, I think its better to just write and let what wants to come out come out.

You can always delete scenes later, and ad the structure upon reflection. I see writing as a discovery process, then you package it into a formulaic, checking boxes script later to appease people who ask questions like "how does this scene move the protagonist closer to their conflict resolution" etc.