This shard says it reduces the Earthforce re-use timer by 5%, which would be 9 seconds (out of 3 minutes), but it actually saves 11.7 seconds.
However, it does NOT stack with the focus effect on the t3 chest piece, which reduces the timer by 21% (37.8 seconds) whether or not you also have this shard.
I don't know if that's the intended result, so I filed a bug. But for now, at least, once you get the t3 chest you might as well find something else to put in the aug 3 slot instead of this shard.