At 90,000 miles is it a good idea to change the transmission fluid?

What is your question?

I have never changed the transmission fluid because the Toyota service book does not include an interval at which to change it; I had no idea I was supposed to change the trans fluid until many miles past 60,000. Then I was told that it was risky to change the fluid because if the transmission has too much debris the changing of the fluid could actually cause problems. Also, all the service book says is that a mechanic should check the transmission for leaks.