Classic search returns ten links and lets the user decide. Answer engines do the deciding for them: they retrieve a handful of sources, weigh consensus across those sources, and generate a single recommendation. If your brand is not part of that retrieval set, you are invisible — no matter how well you rank on page one.
That shifts the optimisation target from position to presence. The question is no longer 'where do we rank for this keyword' but 'how often, and in what tone, are we named when someone asks an assistant this question'.
Across thousands of tracked prompts we consistently see four factors separating brands that get recommended from brands that get skipped.
Run the same prompt set every day across each engine, log whether you were mentioned, cited or recommended, and track share of voice against your competitors. Once you have that baseline, content work stops being a guess.