Inspect, inspect, inspect.
There is no "one shoe fits all" rule.
I sold my 44 years old Prevost with lot of original parts on it and it runs without a trouble.
Don't try that with older 454 engine.
Oil has infinite life in factory bottle on the shelf, but will deteriorate slightly when exposed to engine chemistry and the worse - it could accumulate condensation in the storage.
Modern transmissions are consider "sealed for life" so if the fluid looks good and stays at the level, I would put it at the bottom of priorities.