Ever since eligible_time was introduced, using help_starving_jobs was not as good as using the job_sort_formula. One second a job is not starving and has low priority. The next second it has super high priority. Using eligible_time in the job_sort_formula will allow jobs to slowly gain priority as they wait longer.
Design: PBS Pro Confluence
If anyone has any comments, please post them here. Also, any real world examples of formulas with eligible_time would be welcome.