How do you manage multiple moderators checking the same forum?

[Spinball]

Since moderators can't moderate 24 hours per day, it's sensible to have at least 2 moderators per forum. (In anything but a very quiet forum).
So how do your moderators avoid checking the same threads/posts? It's a waste of time for the same posts to be checked by different moderators. How do you avoid wasted effort?

I'm specifying a system now which will deal with this issue, which I will pay to be created.
I was wondering whether any other administrators deal with this issue.