I do not agree about it, there are instances that the longer the bounty the hithe profit or the earninings. But this assumption is not always right, it is still depends on the campaign.
Yes, i agree it always depends on the campaign whether their project are really promising and or its a kind of project which their has a lot of phases cathegory. But for most its all your decision whether to continue or not if you feel that the teams and admin has no longer made a good strategy to make it work then you already smell the possibility of cheap price ahead.