I have about 500 bricks to cleanup so I can reuse them, the mortar is old and the bricks are soft clay.
What is the best way to remove the mortar and how much time should I allow?
There's two ways off hand that I've used in the past -- knock it off with a chipping hammer, or grind it off using an angle grinder and disk. The chipping hammer is actually easiest because you don't spend time fighting the tool or securing the work piece. Have a stiff wire brush on hand to remove the final bits and pieces that the chipping hammer doesn't get.