[zriha]

The problem isn't brainstorming, as codeflo said, it's important trick that brainstorming establishes a shared understanding that the group came up with the idea.

The problem is what is coming after brainstorming, the execution is the problem. We all have ideas, individually and as a group, but after idea is born, validation and executions are next crucial steps. Then you can conclude that you had a successful brainstorming.