Mets are not a single kind of case. They cause all different kinds of surgical spinal disease based on their location, extent of proliferation, and pathology.
A case for a spinal met can range from an open or percutaneous biopsy that takes 10 minutes to a laminectomy for epidural decompression that takes an hour to a multilevel transthoracic corpectomy that takes 2 days. It can be done for diagnosis, palliation, separation, or more rarely for cure.
They can be frustrating because they are some of the biggest whacks we do, and often patients will still die within weeks or months despite a more favorable prognosis. Sometimes we only do the surgery to debulk the tumor so the patient can safely have radiation without impacting the cord (separation surgery). On the other hand, they can be satisfying because we can give people some of their functionality back so they can live out their days with at least a minimal quality of life.