They should just run the KC Cup/Grand Tourn with another event. It gets boring for 2weeks of just competitive duels and the same decks over n over. They've done it before with a Duelist Chronicles and KC Cup.
No, KC Cup should be once per month and lasted only on the first 7 days of the month followed by a banlist on every 20th day of the month, effective on 27th. Rest of the events run from 8th to last day of the month and that will be the best cycle.