Dress Right, DRESS!
If you are in the military. a cadet program or even a firefighter, law enforcement or EMS, you’ve heard this command at least once.
While you may be amazed with my drawing abilities, stay focused on the info!
Each service, (the Marine Corps Order pushes out to the Navy and Coast Guard) spells out in some detail what is supposed to happen when given the command, Dress Right, Dress. The Air Force specifically states that if an arm is too long, put the hand behind the person to the left.
(TC 3-21.5) “On the command of execution [DRESS RIGHT,] DRESS, the first squad leader stands fast and serves as the base. Other squad leaders obtain correct distance by estimation. The members of the first squad execute in the same manner as in squad drill to obtain exact interval. All other squads execute as the first squad, except that each squad member raises the left arm only for uniformity, actually covering (glancing out the corner of the left eye) on the man to the front.”
(MCO P5060.2)  Says the same thing, more or less. The only difference is that members of the formation meet the fingertips of the individual to their right and the follow up command after, “Ready, Front!” is, “Cover!”. On this command everyone moves directly behind the person in front of them.
(AFMAN 36-2203) “As the remaining members align themselves behind the individual in front of or to the right of them, their shoulders may or may not touch the fingertips of the individual to their right. If the arm is too long, place the extended hand behind the shoulder of the individual to the left. If the arm is too short, leave it extended toward the individual to the left and parallel to the ground.”
Dressing to the center is not usually called so that everyone puts their arms up like dressing to the right or left, but it is something that may be beneficial. Honor guard units dress to the center in different formations, cordons (after dressing to the direction of the VIP) and colors.
One instance where dressing to the center is very necessary is the last part of the JROTC Regulation Drill sequence where the team is marching behind the commander toward the head judge. The team should align like this:
regulation drill, dress right dress, dressing right, dress left dress, dress center dress