I would say I do it at 1/2 or less then what is recomended, look in the
radiator, if there is any buildup its to late, if there is buildup it
should be flushed and new fluid put in. Trans should be red, not brown.
dont forget the differential, on many models it is a different fill and
drain plug. Power steering can be removed with a turkey baister and
Trans fluid goes in my 91, not power steering fluid.

I do mine at about 25-30,000 miles. Use only Toyota coolant!
97 Camry 200,000 + miles so far.

Coolant every two years.
Tranny every 30 K if you are only changing two to three Qts. and not the
torque converter.
The entire system holds around
fourteen Qts.
Good Luck.

Coolant at least every two years. If you do it yourself, every year if
you want.

Tranny fluid, depending on driving habit. If mostly highway then 30K is
fine. If mostly local then 15K is called for.

I'll change out the ATF pan gasket  and strainer. Fram has a nice kit
with a cork gasket, among other brands. Make sure you change the
differential fluid as well.

The differential / tranny seal sometimes leak. And the differeitnal's
ATF fluid will migrate to the tranny, end up costing you a
differential!!!!!