I think this is true for 2019 which is the worst year for bounty hunters because many projects fail and all this affects our rewards. But for the estimation problem, we really shouldn't have too high expectation because we know long bearish will affect many projects. For 2020 it's a bit better and 2017 is the best year.
I think 2020 is the worst year for bounty, I don't see too many successful bounty this year. They have very low budgets and price drops many times after being listed at exchanges. Besides, many projects have failed in the first step