When Uther Pendragon held court, the clerks would not allow any knight to take his seat unless he had a face wound. This custom was discontinued in Arthur's time, when Lancelot, Duke Galeholt, and Ector de Maris became companions of the Round Table; it was replaced by the custom that no companion could take his seat on high festivals unless he had conquered a knight the week before. Ywaine, at least, found the custom irksome. So, most likely, did Kay and other knights.
Also, at the first court Arthur held after his marriage, on the fifteenth of August [Assumption], he made his famous vow never to sit down to dinner until some adventure was reported to him.
Arthur held five courts annually at which he wore his crown: at the feasts of Easter, Ascension, Whitsuntide [Pentecost], All Saints, and Christmas. Easter was the highest festival, Whitsuntide - the renewal of Easter joy - the most joyful.
At the Pentecost court of Galahad's arrival, the Queen and her ladies appear to be dining apart from the King and his men. Other scenes, however, show men and women dining together, those of highest rank taking the highest seats on the dais. Serving at table seems to have been an honor - sometimes, at least, for the servers as well as those served.
Clearly, the higher-ranking were those who served you, the more were you honored - on the Pentecost of the Grail, Malory records that young knights [probably as opposed to squires as pages] served at table; when Arthur feasted Kings Ban and Bors at All Hallowmass, near the beginning of his reign, Sir Kay the seneschal, Sir Lucas the Butler (Lucan), and Sir Griflet served, or at least "had the rule of all the service that served the kings"; according to Vulgate IV, four kings and other high barons served at Arthur's table on the Pentecost of Galahad's arrival [perhaps Malory's serving knights served at the lesser tables]. In the tale of Gareth Beaumains, the various knights he has conquered during his adventures show up and as honors beg to serve as his chief butler, sewer-chief, wine-server, and so on at the feast.
Courtly Love | The Legend of King Arthur