BLMs will (should) click it off on trash because the extra speed prevents them from refreshing enough MP to do their rotation, resulting in a DPS loss, so don't throw it at a BLM on trash. If you use it on a BLM during a boss, however, you will be that BLMs new best friend.
For the other jobs, too many Arrows can lead to early depletion of TP/MP. In a light party, I'd recommend burning it for an Extend. In full party content that will last longer than couple minutes, if there's no BLM, Redraw. If it's a short/easy fight, the resource depletion won't be an issue, so you can use it on someone based on the priorities the above posters have suggested.