The prevailing belief is that generative AI simply shaves minutes off any writing task, freeing brains for higher‑level work. In reality the model hands over a polished‑looking draft that lacks the author’s mental scaffolding, so the reader must rebuild context from scratch. The mind’s rehearsal buffer—its internal sketch of arguments, evidence, and narrative flow—gets bypassed, and the brain has to re‑populate it after the fact.

When a senior analyst at a consulting firm asked an LLM to draft a market‑size memo, the output looked complete, but the analyst spent the afternoon tracing each assumption, flagging missing citations, and re‑ordering sections to match the firm’s logic. The extra effort stemmed not from the AI’s speed but from the hidden cost of reconstructing the mental model that would have formed during a manual draft. This “rehearsal deficit” erodes insight because the writer never internalizes the data, and the reviewer never sees the original reasoning path.

Teams that treat AI as a one‑click solution end up with more revisions, slower decisions, and a gradual atrophy of analytical muscles. The antidote is to let the AI serve as a sparring partner, not a substitute for the thinking that precedes the first sentence.