I have found that it's much more profitable to vote on undiscovered posts, as there's no competition. A user that will always buy votes (or more important, is very popular, so guaranteed high payouts) - bots and humans alike will latch on to those. It'll start a bidding war where you'll often have to vote at 15 minutes or earlier. It's stressful and when I tried that it was never as profitable as just voting on exceptional but undiscovered posts.