Tell the story that needs to be told, in the way it needs to be told, to the length it needs to be told.
Don’t poison a story by insisting it must be an apple when it’s really an orange.
Don’t stunt a story by forcing it beyond its natural growth nor by forcing it to grow in a box too small.
“Genres” and “standard story lenghs” are publisher’s artefacts, not part of storytelling.
Breakthroughs don’t come through abiding by conventions and working in boxes.