The question
When growth in your core topic is slowing and you are weighing a move into an adjacent area.
Your core topic is maturing and you are deciding whether to build authority in a new adjacent topic area.
Why it matters
Expanding before your core topic is authoritative spreads thin coverage that ranks nowhere and confuses your entity, while never expanding caps growth once you dominate the original space.
How to decide
IfIf you already hold strong authority across your core topic
ThenYes - extend into an adjacent area where your existing authority transfers.
IfIf the new area is closely related and serves the same audience's needs
ThenYes - natural adjacency compounds topical authority rather than diluting it.
IfIf your core topic still has unfilled gaps and weak coverage
ThenNo - deepen the core before broadening; half-covered topics rank poorly.
IfIf the new area is unrelated to your entity and audience
ThenNo - an unrelated pivot fragments your authority and confuses engines.