Sabbatical derives from Sabbath and refers to the idea that once a week we pause and do other things than work to refresh ourselves in part by remembering a broader picture of what life is about, including our family and community. And Sabbath applies as well to agriculture and how good farmers refresh the soil by planting a cover crop to let the fields renew once every seven years. Sabbaticals are rooted in these excellent ideas. Think of them as the option year.
Yet many districts have restricted sabbaticals in the name of saving money even though administrative pay has increased substantially over the past decade. The procedure for granting them often presumes they are bestowed by high-level administrators and sometimes union leaders as well. Furthermore, many districts limit the number given regardless of the size of their faculties and/or limit what teachers can do with them once granted. Often travel is held in lesser regard than graduate academic work. Others are granted at reduced pay or for half a year only, and I know of no one who has gotten more than one in an entire career. And as to taking a Sabbatical, it comes with the requirement that you must return to your district to "pay it back!" or if you don't return, pay it back in cash. Yet many countries including the Chinese encourage study and work abroad. This is an international world after all.