These rules keep a tab left open in the background from inflating the numbers. Even so, time on a page shows attention in the browser, not that someone read or understood the page.
Sessions and time per page count only after the recipient agrees, on the PDF page, that your company may see how long they read its documents. Until they answer, and after a refusal, HawkOpen measures nothing, shows you no session and keeps no IP address.
For now PDF tracking is a preview: HawkOpen accepts files only once external file scanning is switched on.