“And what was the point in sending Benteen off on a wild goose chase?”
Custer’s point was twofold: (1) He wanted to block any attempt of the hostiles to flee toward the immediate south; (2) He did not want a repeat of the Washita fight which nearly cost him his hair and those of his command (in attacking Black Kettle’s camp on the Washita in 1868 Custer failed to determine the existence of several other, larger camps nearby, and when those camps got wind of the attack on Black Kettle’s band they came out in force and could very well have wiped out Custer’s command — as they did Major Elliott’s squad earlier that day — had Custer not held a lot of women and children from Black Kettle’s band hostage).
I know some think that was Custer's plan - if he could get into a position to separate the women and children from the warriors, he would then be able to intimidate the warriors into returning to the reservation. Maybe that was the point of Reno's attack - The warriors would focus on attacking Reno while the women and children would flee in the opposite direction. It would have been nice if Custer had bothered to inform Reno and some of his other officers who survived what "the plan" was.