As for ATF, if you haven't changed it up to now, the general advice is that changing it now may actually be more likely to cause problems.

I know some people follow that advice but I don't. The AFT fluid is still bright red and there are not any transmission problems. I don't see where leaving old fluid in a transmission aids the longevity of a transmission.

I don't either, unless the clutch friction plates are already pretty worn, which would tend to be indicated by a brown fluid. (Replacing fluid in an automatic transmission with worn friction surfaces tends to hasten failure, as the detergents in fresh fluid tends to wash away more friction surface from worn clutches.) Changing the fluid and filter in a transmission w/o worn clutch surfaces is a good idea, IMHO, as contaminants and deteriorated detergents in the aged/used fluid can cause more slippage and, therein, more premature wear of the clutch disks.

I once worked in an automatic transmission repair shop - Their extended warranty included mandatory fluid and filter (and governor, if equipped) replacement at regular/specified intervals. 2 of the shop's experienced mechanics told me not to replace fluid that evidenced "burned" clutch plates, as fresh detergents merely served to wash away little remaining clutch surface, the only case in which they recommended not changing at specified intervals.

FWIW,
Bob