for these 6 days old posts:
Here some sample of post promoted in the last days :
This flower picture buying 124$ vote at 5th day https://steemit.com/colorchallenge/@ekaterinka/73poqn-colorchallenge-sundaypurple
$410 on 5th day on a simple picture that say "Happy new year" (apparently it's a meme)
About 99% of people buying votes on their post older than 3.5 days are doing it for pure profit by taking from the reward pool while enriching mainly early ninja miner and vote selling bot operators. Not allowing votes past 3.5 days will give us more time to detect and counter high votes purchased on very low quality content.
Unless votes sellers become GrumpyCompliant in the next 7 day @grumpycat will push the vote buying abuse ratio even closer to 100% by flagging the most legitimate use of post promotion at the worst possible time...