When are you supposed to wear a staggered right ribbon holding bar?

I think is a preference thing. I am a bit more broad in the chest so I my lapels really don't cover much. I do offset my CIB. I just find a ribbon rack without the spaces. I didn't think they were that hard to find but I never found what at Bragg or in the Army. I did find one in Columbus. I had a 1SG in IBOLC tell me to try to get the one without the gaps due to have too many rows. It has to do with it looking clean. I agree. It saves space and it looks cleaner to me.

USMC verbiage: When more than one row of ribbon bars is worn, all rows except the uppermost will contain the same number of ribbons. If the number of ribbons worn causes the ribbons to be concealed by the service coat lapel/khaki shirt collar (one-third or more of a ribbon concealed), ribbon bars will be placed in successively decreasing rows; e.g., four-ribbon rows, three-ribbon rows, two-ribbon rows, single ribbon. The left (outer) edge of all decreasing rows will be in line vertically; except that when the top row presents an unsatisfactory appearance when so aligned, it will be placed in the position presenting the neatest appearance (usually centered over the row immediately below it).

Old regulation used to say when more than 50% of an award would be covered. Sadly the verbage disappeared with the rerelease...