Skirmishers were normally assigned by brigade or regiment, not by company. In the case of Shaver's Arkansas Brigade at Shiloh, two companies were deployed as brigade skirmishers when the early morning advance began. They relieved Hardcastle's Battn, picketing for Hardee's Corps (three brigades) in the hours before dawn.

Unless the field before a line of battle is open, which wasn't often the case, exact distances are hard to define, and even more difficult to maintain under fire.