Your post made me stop and think. I manage the quality org charts for my company and utilize a standard naming convention. Updates are made as employees come and go or as changes in the structure occur. Org charts are kept for the duration of the record retention period. I would be interested in learning more from others, too.
In the past when I have had to maintain/update, we have used Visio to make the flow chart, it is very helpful with the visualization. As for maintenance, we had regular, scheduled food safety meetings/management meetings, where we would use that time to make updates, have notes for our GFSI certification etc. I have heard of changing as the food safety team changes, which depending on the team/company can be rare or more frequent.
I'm not sure if that helps much, but love the discussion.