Other spacings

For nearly all drill and maneuvers, Open Order is the widest necessary.  Open Order is sufficient to permit doublings. 

There are wider distances, too.  These were not often used historically and today are rarely seen among re-enactors (with the exception of the first one below for ranks of pikemen):

• Double Open Order (which Colonel Barriffe terms "Double Distance") is 1.8 meters/12 feet between soldiers.  One possible use of this distance is for pikemen on the march.  Such a wide distance between ranks leaves room for pikemen to trail their pikes while marching.
• Triple Open Order is 2.7 meters/18 feet between soldiers.  Barriffe doesn't include this.  This distance, though, may provide room along the route of march for pikemen to cheek their pikes. (To cheek a pike is to place the hand around the point to avoid inadvertently sticking someone, but this leaves a lot of wood dragging behind the pikeman.)

For marching re-enactors, these two distances present the temptation for audience members to cut through the formation on some urgent errand like fetching a beer.  Today, we don't have the options our ancestors did who could scold, arrest, or even beat any civilian who dared trespass into a formation.  (Or possibly pressing an errant male civilian into service: "Since you like being among my soldiers, you will join us!")  Our only recourse is to avoid presenting temptation as much as possible.