One channel trunking [used by some of the unidens] is different from only entering One Control Channel in a Trunk configuration.
Altho your system [which one?, send a link] has only stayed [during your experience] with the one frequency, this does not mean that
they do not have 1, 2 or 3 alternate channels [assuming Motorola] which could [YMMV] appear at any time.
Always best to include any/all of the CC/Alt CC's during programming, to save you from any future troubleshooting
I listen to a very small phase I trunking system. Although there are several frequencies in the trunk, only 1 get's used as the data control channel. Are there any advantages to setting the system up as a one channel only system ? .