Create distinct categories before generating ideas. If the categories are meaningfully different, the ideas inside them are less likely to repeat each other.

Repetition usually happens when you brainstorm at only one level. Moving across customers, product, channel, operations, or economics gives you different lenses.

If the question is how a gym can grow revenue, five promotion ideas are all one family. A stronger brainstorm could cover pricing, membership tiers, new locations, partnerships, and ancillary services.

Practice 30-second brainstorms where you create three categories first and only then add ideas.