Why Content Length Isn't a Ranking Factor (But Relates to One That Is)
The confused correlation
Long content tends to rank. Not because it's long, but because it's often more thorough — which matches more search intent variants.
Write until you've answered
Write the length required to fully answer the intent. Then stop. 800 words of complete is better than 2500 of padding.
The comprehensiveness test
Compare your piece to the top 3 ranking pages. Do they cover topics you don't? That's your gap. Close it or admit your page won't compete.