If Custer thought that he had the time, he would have delayed his approach march, maneuvered to get his columns to positions of mutual support, tucked in his trains, and take time to find out where the other columns were.
He did none of these things.
I have seen the same thing in combat and in training. Most commanders tend to think that any delay will shift the initiative to the enemy. Sometimes, that is correct, but sometimes hasty attacks become uncoordinated, piecemeal efforts that fail.
He was counting on Reno holding out his small skirmish line and not retreating. He also didn’t anticipate the hilly terrain that cost him precious minutes in his approach.
I’ve always thought he should have brought Brisban’s 2nd with him when he broke away from Terry. Egos and everything that goes with them meant that he wasn’t going to share the glory though.