It's not always about how long the bounty duration lasted for, I've joined a bounty for months and still end up with few dollars, I think 12$ maybe, and there are bounties that will just take you for 4 weeks and you will get a surprising reward in the end
Yes, because each bounty is not the same in terms of allocation as well as in terms of management, so that the earning of rewards for each participant will obviously be different, so because remembering this, each participant is always told to always be more observant in seeing and choosing bounties.