Custer's strategy, since he'd become convinced his command had been discovered, was to attack the village from several directions to prevent the Indians from escaping. It worked at the Washita in '68 so he would try it again.
The problem was, at the Washita there were a number of additional camps downstream that forced him to retire after burning the village. Although he'd sent Benteen with his battalion to scout for camps south of the one he'd located on the Little Big Horn, they were all congregated in one large "village" comprising a number of camps. By separating his command, he invited defeat in detail.
Spot on again... you know the history of the battle. The Little Bighorn encampment was very compact for its population size. At the Washita... it was dispersed. Sadly, Lt. Elliot learned of this in the worst way possible.
Also, since the Washita encampment was dispersed, Custer's 7th could put on a “bold front” and intimidate the slowly massing warriors who were in his immediate front.