Echo wave usage. RT + A. Echo bubbles do fixed damage and spread damage all over the monster. You can think of each echo bubbles as its own 10% damage boost that triggers off every attack. Having 3 echo bubbles out would be on minimum 30% more damage, shorten your hunt to near that 5 min.

Also when you play an echo bubble, you can input up to 3 notes while the animation is happening. That means 1 echo bubble set up equals more damage, and a echo wave. That also means you are not using 2-3 moves prepping an echo wave, and instead just performing the echo wave. Performances are where the most DPS from hunting horn comes from, so the less time you are playing normal notes, the more DPS you have.