I have PoJ and I stop running at approximate distance for a bout 2 sec and run again.

PoJ is best in level boosting where you can pull the entire room quickly and effectively.

@80 POJ works too when you want your DPS steam to standby and Paladin pull the trash mobs.

PoJ is best also in chasing Alliance

The enchant is only half of PoJ and the difference is noticeable. Though you can apply this to your followers

You may want to get this quest reward trinket also for your followers
http://www.wowhead.com/?item=2820

Though in general Speed buff don't stack