As a bit of follow up, and comparison with the incident hikermor posted in another thread, most "SAR" incidents are resolved fairly quickly. Nationwide, something greater than 90% of SAR incidents are handled in the first "operational period", in other words within the first day. Often these are more rescues rather than searches.
For example, a hiker is reported missing. A couple of hasty teams are sent up the most likely route. The hiker is found with an injured ankle and is brought down. Or, as in the example hikermor posted on another thread, someone reports an injured or trapped person. A medical and/or rescue team is dispatched to a known location, and deals with the incident. These kinds of things happen all the time. Often, they don't make the mainstream news at all, unless there is a fatality.
In a much smaller number of cases, the incident extends over several days, and may involve dozens, perhaps even hundreds of people, from multiple agencies and organizations. Typically (though not always), these are searches for missing people. When incidents grow this large and extend over many days, management of the operation becomes very complex. A poorly managed incident can lead a bad outcome for the missing person, and can unnecessarily endanger rescuers.
Years ago, after a number of very large, very badly run searches, with very bad outcomes,
NASAR developed their
MLPI course. This course teaches people how to organize and run large scale land search operations. More recently, other specialized courses for using the Incident Management System in large ground searches have been developed. The NPS has been one of the agencies heavily involved in developing these programs and getting their people trained up.