Formations are entirely METT-TC dependent. What are your Mission objectives and constraints? What is the disposition and strength of the Enemy? What spacing and formations are they using? How much Time do you have to reach your OBJ, ORP, or BP? What Tactics are the enemy using? What type of Terrain will you be moving across. What type of terrain will you be moving onto? Are there any Civilian considerations? (Not applicable to SB at this time of course...) All these factors go into my decision as to what formations and spacing to use.