So the guild (one of many guilds) is personally responsible for setting up the altar so when Eucharist is commenced everything will be prepared for those commencing it. Afterward communion is done, and the service is let go, and in short, its job is to make sure the "third act" is done smoothly since often the biggest service is at 11:00, and the Cathedral will have 500 people in it. I mean sure every service has the Eucharist, and then Communion enacted, but the most noticeable impact is always felt in the 11:00 am one since that is when the largest crowd comes.