Why have we done it, heck who knows. Do the Elk care, I mean seriously speaking here do the elk really care!
Do we think we fool them for a 2nd if we cast our sounds left or right that we can redirect their approach with any real world significant results. If so I sure haven't seen it. Elk can come from great distances no matter which way or which direction I faced myself or my bugle tube & walk right to the spot, time & time again & year after year!
No doubt in our minds we want to think it's redirecting traffic but with over 60 elk down between my Son & I & near that many more we've called in over the years for friends & family elk come to the caller & sometimes circles a bit to get the wind of the caller; not in the direction the caller or which way his bugle is facing. -- If we want to redirect their approach in a setup the Caller needs to actually move to a different position to direct their approach to get the bull to pass by us or the shooter.
P.S. -- Not a single Elk has ever been called in because we cow called through our bugle, but boy the bulls we've called in with it is off the charts! food for thought! Use what works for you!
ElkNut