If only two posts daily, four hours gap is attainable but if three then we have a problem, bounty manager should have no time restriction that long the most important thing is the posters are not spamming and they contributed on various topics.
Three posts a day imo is still possible, I guess it just depends on how frequent you can browse the forum but anyway if you check the replies above the gap was reduced once again by the manager. And if they fail to meet the requirements they still receive a portion of the said reward so overall the campaign rule for posting gap is less punishing.