I write detailed instructions/information for each system for management of the system and for the mobile units programming. It explains what the reasons are for why the config are done in a certain way and what effects it will have on the system. It's then easy for anyone wanting to program a mobile unit, as well as a system manager, to read that to understand what will happen if some values are changed in a codeplug.
If the system uses roaming between sites a user ID can be configured in the system to use site 1-2-3 but not 4-5 as those belongs to another district but could have a better signal strength at some occasions. If a new userID are allowed to use site 4-5 then that TG could not be allowed and under certain conditions that user are stuck on that site and can neither transmit or receive. Or the added TG load, especially if it includes a lot of data information like GPS locations and such, could load the site more than it is designed to hold and will be overloaded.
So it will be complicated to alter codeplugs if the tech guy do not have all the information needed. It's usually one senior tech that have a full understanding of the system operations, and have access to those detailed instructions, that will advise on how to change codeplugs or will supply ready made plugs to be loaded by a junior rank tech. So any type of education on how to do manage codeplugs will need to include the full understanding of the workings of the whole system.
/Ubbe