Not all. I just scrolled through my recent curation rewards for the bigger ones and this one has a good ratio towards curators: https://steemit.com/science/@redalex/german-scientists-have-developed-an-effective-method-of-absorption-of-carbon-dioxide-from-the-air
It changes the % allocated because curation reward is dependent on stake. If a good amount of stake donates curation rewards with votes before 30 minutes, it means more curation rewards in total will be donated to the post author.