My experience is they typically a few frequencies which were there for test and alignment purposes during manufacture. Often the lowest and highest frequencies in the range covered by that model, and sometimes a center frequency. If there were more than a couple they were the same freq with CTCSS, DCS, 2 tone etc to test the signalling functions.
As an example I just looked at a saved factory program that came out of an F5021, was as follows:
136.1000
155.1000
173.9000
155.1000 with DCS 023N
155.1000 with CTCSS 67.0
155.1000 with CTCSS 250.3
But I wouldn't count on any factory programming to be consistent, it's just whatever is left in there from manufacture. A couple factory programs I opened up for different radios just had a single channel programmed of 136.0000.