If your riding western your horse relies on feeling the shift in the balance of your reins before they come tight. If your reins are too light it is harder for your horse to feel the change of balance. I have a horse that I ride in a spade bit and the reins rarely have the slack taken out of them because I have chains between the reins and the bit that signal the horse that a change is coming so he gathers himself and breaks at the poll. The same philosophy is behind the use of slobber straps on a snaffle bit. It gives the horse some warning that a change is coming.
There's nothing like the Rockies in the springtime... Nothing like the freedom in the air... And there ain't nothing better than draggin calves to the fire and there's nothing like the smell of burning hair. -Brenn Hill