Only in abstract - before you get to do it. When you do start to write a specific poem this doesn't hold anymore, and a big part of the art is fitting the form you chose.

Imho the "art in poetry" begins when I had that dinner with that fascinating woman, and I had the "porch test" and in that test it was raining, and I came up with a haiku. But not (only) on the haiku itself.

The poet is limited to symbols. And every poet comes up against these limitations.