Starting from 30 minutes your post has been posted the reward for curators is 25% from your post. Voting last minute allows to do shady things and not been caught on time by the flaggers. i.e. huge self-upvotes which for some are linked to misbehavior and reward pool rape.

If you want to see how bid-bots work, please check my post about the mentioned and alsoabout what I recommend personally SmartSteem.