Extractable content answers one question completely within a single self-contained passage of roughly 40 to 60 words, near the top of the page, without depending on surrounding context. It survives being quoted in isolation.
Front-load the answer. Content that builds to a conclusion after 600 words of preamble is rarely extracted.
One question per section, with the question as the heading.
Avoid pronouns referring back to earlier paragraphs — an extracted passage loses its antecedent.