blockchain consensus mechanisms have an idea of finality. That is how many blocks deep into history a block has to get until we are certain that it is in our history, and wont disappear in a fork. It is also the amount of time that validators need to leave their money locked up.
Oracles also have an idea of finality. It is the amount of time that reporter's safety deposit needs to be locked up after a judgement.
The minimum rate of cost of operating an oracle is (the sum of all the money judged over during the last finality period) * (the interest rate)
If we use the blockchain validators for part of the oracle consensus mechansim, then the oracle finality period needs to be long enough in the future so that the blockchain validators can realize the scandal of a lying oracle and react to it.
The maximum amount of judging that can happen in one oracle-finality period is 1/3rd as much as the amount of money that reporters have locked up.
In the case of Flying Fox, the oracle-finality period will be decided by the validators. I am planning to start it off at 48-hours.
If we could get 12% of the money on the blockchain participating in the oracle, then that means we could judge over about 2% of the money every day.
If a massive bet went through that used 60% of the money on the blockchain, it would take 30 days to be completely judged over.