A network search would be useful if the NIT (Network Information Table) contains information (Transponder Numbers, Symbol Rate, Modulation, FEC) about all of the transponders for a provider.
An example is Dish Network where the NIT and SDT (channel information) contains all the information so that that Dish Network receivers can easily lock onto all the channels without having to do a blind search.
For FTA receivers I think this feature is used in Europe.