When a candidate is good enough, he can be accepted very quickly without deadlines while deadline would increase the waiting time. Deadlines are only appropriate when recruiting a large number of candidates (think public servants procedures) as due to the law of large numbers, we statistically end up with a more or less similar number of good candidates.
On individual positions it is the opposite. There isn’t enough applicants to have the randomness smoothed and we can sometimes find people in a few weeks while other times it takes a whole year.
At Kleros I never regretted taking more time to hire people. I think the DAO should do the same, as those are hard to fill positions and it’s better to take time than to fill them with suboptimal candidates.