Transmission oil change

I have always heard that you should change your transmission oil about every 50,000 Km. Recently I had to take my van into a dealership here in Japan for it's shaken, or road inspection. I asked the mechanic if I needed to change the transmission oil and he said if I did it would damage the transmission more than leaving the old oil in there. He claimed that the debris in the old oil were what were keeping the gears from slipping and causing more damage. This seems to be a very prevalent view here in Japan after talking to various people. They expect the KZ series to run 200,000 km with this method. Do you think I should follow this seemingly crazy method or insist that they change the transmission oil?

I'm not qualified to say yea or nay but not changing lubricants is contrary to everything I've ever heard. My impression is that most Japanese drivers don't clock up large numbers of kilometres, and change vehicles while relatively new. If that is correct they may never have to consider the best longevity of components.

If it's red leave it as said.

No debris in the system that is what the filter is for.

If it is not red or smells burnt on the dip stick change it.

I believe that the factory service interval for oil changes in Automatics is 40,000Km.
That's when it should be changed and sooner (every 20,000Km) for severe service (Lots of 4wheel driving)

If you don't change the oil and the vehicle is still under warranty, kiss that warranty goodbye if something fails.