A lot of what needs to be programmed depends on how the Unication's actually function with the P25 standard. If no one has ever noticed, the actual information that a P25 control channel broadcasts is quite informative...alternate control channels, band plan, adjacent sites (along with their active control channels). The reason for this, the subscribers have the ability to pull information off the air and learn the systems by writing information to their flash memory. This allows them to adapt to changes (new sites, updated band plans) and allows for a nifty little feature called spectrum wide scanning where as long as the subscriber knows the system ID, WACN, and partial band plan it can go find an active site without having any other programming (such as control channels or site aliases). Implicit systems (which are becoming rare these days) however do not advertise any of this information simply the call routing directions (i.e. TG 3DE, channel 02-256) and is why many subscribers are fully programmed.
How likely are control channels to rotate? With today's standards which include climate controlled shelters and active cooling on equipment, most repeaters can run for a decade or more as a control channel. As a result, the only time many will roll is for maintenance (Motorola for example recommends annual alignments which will require the control channel rolled) or if interference is detected on the uplink (there are some systems along the I35 corridor in Texas where this happens two to three times a week).
Play with it. If it were me, having had some not so great experiences with the G5's in multi-site systems, I'd program all of the relevant control channels for a site. Just my personal experience with the G5 though.
