Given the formatting required for easy parsing (either by ATS or by humans) you can count on every employer and every role to require at least 3 or 4 lines at a

Given the formatting required for easy parsing (either by ATS or by humans) you can count on every employer and every role to require at least 3 or 4 lines at a minimum (company, timing | Job title | some descriptor or activities and/or successes | line break before next job), I'd say if you've had more than 3 or 4 meaningfully relevant roles you could make the case for a second page. I don't think 3 or more is often warranted, at that point you need curation more than you need more "space"