It really just depends on the illness and how it progresses, which is hard to predict. Both my grandparents died of cancer; my grandmother spent close to a year

It really just depends on the illness and how it progresses, which is hard to predict. Both my grandparents died of cancer; my grandmother spent close to a year in a hospice, using quite a lot of morphine, slowly fading away, while my (otherwise fit and active) grandfather went from "I've got a stomach ache, better see a doctor" to "dead" in about two weeks.