Gunslinger Deadeye Shot. Does that mean the character can use it repeatedly to get advantage on every attack in a turn?

I was just rereading the Gunslinger v1.2, and I noticed that there’s no action use tied to Deadeye Shot. Does that mean the character can use it repeatedly to get advantage on every attack in a turn?As long as they have the grit points to spend, they can

— Matthew Mercer (@matthewmercer) February 11, 2018