how long the Bounty campaign usually gives the Prize
The time of distribution of prizes is the authority of the bounty manager, usually for the gift distribution already pinned by the bounty manager on the thread. If there is no announcement, you can ask the manager. Distribution of prizes from bounty programs that I follow there are 30 days and some are 7 days after the ICO is completed.
It does not depend on the bounty manager because most of the bounty manager will do calculation and turn it to the owners for payment. I hope owners will take time to distribute the bounties to the participants. Sometime they will take more than month for distribution of bounties.