I use written contracts all the time, with pay-per-show.
It does three things:
Allows me to have long-term usage of talent without them being poached. Ideal for long-term planning and storytelling.
Allows me to get the talent I want, without breaking the bank, by having to pay them on a monthly basis.
Allows the talent to get more experience and ring time elsewhere if I'm a smaller company without a TV show, or a somewhat limited schedule.