How does your A/V system work? Who knows the exact configuration? Is it just the TD? That may be well and good, since he is the expert; but what happens if he quits? How will you fix things if you don’t have a clue about the wiring!
Every A/V setup should have a configuration manual. This can be hand drawings, but using a computer will make it a little clearer. It should document the essential connections between major components in audio, lighting, and video. That way, there is something written down that explains it all. Doing this will capture the institutional memory of how things are wired together, so that anyone on the tech team can figure out a problem – even when the TD is away.
Sure, it takes time to document things. But you can do it at a high level – i.e. component by component. You don’t have to label every single wire and document the wiring harness. But you do need to revise the configuration manual periodically as new equipment comes in, so that it stays up to date.