Back in the old days (1984-1995), almost all of the figures sold in sets were also available as single figures. For example, the old glossy Seaforths, Afghans, Cavalry, etc. were all available in everything from huge presentation boxed sets like "The Last Stand of the Seaforths" or complete 16 mounted figure squadrons with an officer, buglar, and 14 troopers, as well as 6-8 figure infantry or 4 figure cavalry sets of related figures, and single figures (which sometimes came in little hunged see-through plastic boxes with cool K&C lables on top).
In the matt era, single figures from larger sets are a rarity, and only came as special figures or repaints.