Most of the ~1 hour activities can be extended for as long as you have time and energy
Silver Alerts are issued for missing endangered adults, high risk missing people and missing endangered children, often those with a mental or physical disability. Drive around and keep an eye out.
Check media, Facebook pages, and search organizations to join a local search, especially for endangered subjects, where every second counts.
It's a sad truth that, in many instances, skeletal remains have been found by hikers, hunters, runners, etc. Look for things that don't belong - clothing, shiny objects, artificial mounds, etc.
Volunteer to post flyers, deliver them door-to-door, attach them to poles, etc.
If you have surveillance cameras, including personal doorbell cameras, in an area where someone went missing, check them - they might have picked something up.
If volunteering or interacting with the homeless, check to see if you recognize any from local missing persons lists.
Check state / local missing person lists to see if everyone is on NAMUS and The Charley Project and vice versa. If not, ask the listed coordinator/agency about adding them.