This season, I was paying attention to the "warm-up" channel at the majors. Here's a list of players who used an alignment stick during warm-up.

PS - These are the best players in the world, but they know how important alignment to the target is that they use an alignment stick to help calibrate their eyes.

Rory McIlroy
Tony Finau
Jordan Spieth
Phil Mickelson
Rickie Fowler
Jason Day
Dustin Johnson
Billy Horschel
Francesco Molinari
Patrick Reed
Daniel Burger
Tiger Woods
Beyong Hun An
Paul Casey
Charles Howell III
Matt Wallace
Justin Rose
Patrick Cantlay