I just tested it with England. I sent Cecilia to Rome with move_character and built relations to perfect. Then called Crusade on Antioch and used move_character to get William there with a Ballista and took it in one turn.

I was immediately able to call another Crusade.

Still had a problem getting Pope to accept some of the Crusade destinations, but I imagine that if the Pope was particularly angry with a Christian faction then he would allow a lot of Crusades.