I have a friend who rebuilds auto boxes and his view on oil changes is depends on how it is used.
A car used on motorways and long distances probably every 48 to 60k is sensible as oil is cheaper than a box. On the other hand a car used around city and town mostly it is probably better to think about doing it every 24 to 30k. Look at the colour of the fluid, if it is clean and has no bits floating around in it you are probably OK.
It is shocking when you go to his workshop to see the condition of some auto gearboxes, he had one recently that actually looked like somebody had just put a pile of cogs and components in a casing and hoped for the best.
