Why are physiological processes usually controlled by more than one hormone?

Answer 1

Usually for balanced control, rather than the amount of a hormone doing the control and depending on its absense for something, most processes under the influence of hormones are turned on or increased in activity by one hormone and decreased or shut off by another. In addition, a hormone that is shutting down one process may be turning up another that depends on the first or can not work while the first is working.