Is brainstorming witha group even a thing nowadays? Last time I did some brainstorming with a group was in a high school.
With my teams, we'll meet, chat about a problem, go out separate ways for a while, then regroup. Or, we'll send one expert off to do some solo thinking/analysis, and bring it back and we'll all discuss it, then send that person off again. Which way depends on the problem and the individuals involved.