The longer you work, the more work you do, but the total reward does not increase, of course it is a loss. So don't participate in projects that have a long time, too many variables, it is likely to fail in the middle of the problem.
This is because the team has difficulty reaching softcap or hardcap so that the longer the bounty then the fewer the earnings, and even we should be ready if we do not get anything because the team failed to reach softcap or become a scam.