In practice
One H1 that states the subject, then H2s for the questions the page answers. Nest by meaning, never by font size.
Headings written as real questions are what get lifted into featured snippets and assistant answers.
Why it matters
They are how a crawler, a screen reader and a skim-reading visitor all parse the same page.
A clean heading outline is usually the difference between a page that can be quoted and one that has to be read whole.
Related terms