Having a group brainstorming session isn’t wrong but it shouldn’t be thought of as a single event. Instead, group brainstorming should be considered part of a process that includes sufficient time for individual thought.
The point of brainstorming is to set aside uninterrupted time to think about how to solve a problem. This doesn’t mean a brainstorming session has to always be done in a group setting to be effective.
Via Kenneth Mikkelsen