The way Delta does premium time is very different from United from what I hear. It sounds like Delta has various limits/thresholds/triggers for green slips and silver slips. United is literally first come first serve in the real time window (after 0900 local day prior), and seniority based outside of the real time window for all opentime premium trips. Zero limits on anything, just FAR rest/duty/block limits. Meaning, the senior people can AND do drop their entire schedules and try to vacuum up all of the premium time legally allowed. The double edge sword that stops the senior folks from taking it all is the tiered premium percentage system the company uses. It helps the company but also helps AND hurts the pilot group as people will essentially undercut eachother. The company will generally (depending on urgency) post the trip at 50% premium. If no bites then 75%, and if still nothing then 100%. This allows folks to get a bite at some premium time before it goes to the most senior pilot with a 100% premium pay auto pickup in.