Schema Pro Documentation

A field marked Filled automatically if left empty pulls from the post being rendered:

• Headline / Name — the post title
• Description — the excerpt, or the first 55 words of the content
• Image — the featured image
• Author — the post author's display name
• Published / Modified — the post dates
• URL — the permalink
• Publisher — your site identity

This is why one Article schema targeted at all posts is usually enough: every post fills in its own values. Type something into a field only when you want to override the automatic value for every page the schema applies to.