Coward actually rather famously would never run much longer than 3 months as an actor, He confessed he got bored, and would rather be writing or living his life. Stars used to regularly commit to a year initially. If your show is star driven, you need a start long enough to recoup. Thats how it worked for a long time. Streisand - who was becoming a big star with 3 solo albums released before FUNNY GIRL opened. She stayed in FUNNY GIRL for 21 months.