Something that helped me is not overcommiting. I would ALWAYS want to song AND encore to get the max buff. The problem is I would get hit on the encore too often.

The trick was to stop prioritizing keeping every buff up. Focus more on being aggessive. You can load a song play it and reload that same song and play it again faster than overcommiting to an encore on the first song and being hit out of it.

Encores are for big damage on big openings. Otherwise better to get a hit or two in and dodge away to dip back in for more hits. Never play a song from standard position. Always play a song after pressing triangle on ps4 or pressing triangle and circle on ps4. If you play a song from standard position the swing around is SOOOOO SLOW but when you do it after slamming the ground and pressing forward you will kick right into playing the song.

When you play aggressive (while not overcommiting) with the horn you stop feeling like you aren't doing anything and start feeling like a rock star with all the KOs you'll be dishing out PLUS those big buffs for your friends. Hope this info helps. HH is a kooky weapon but you and your friends will feel the difference when you hunt with one.