Freezer on refrigerator continually runs
well, if its 20 years old, and still cooling NORMAL in both the freezer and fresh food, with the controls at normal middle settings. then no, you dont need repairs. if temps are a little warmer, or even a little colder than normal, or in order to keep it at a normal temperature, you have to adjust the controls to a colder setting, then you might need a repair.
if it is cooling ok, and running more, the tradeoff of running longer, is its drawing less power than it used to when it ran "normally" so the trade off is about equal. factors that can make it run longer, is it near a heat source, is it sitting in the sun most of the day, is there not much food inside, is it being opened frequently, is it near the stove, are the doors sealing good, all four sides of both should be contacting the face of the fridge, are there any tears, rips or gaps in the door seals, i could go on.