70k Mile Tranny Filter Replace

I drilled my pan in the corner right under the dipstick and drain it into a bucket so it doesn't make a big mess.
Then a sheet metal screw in the hole and a dab of RTV on the inside of the pan around the screw shaft for a good seal and put it back on. (no dry time)
Now when I need to drain it I just put the bucket under it and take the screw out.

The thing with trans fluid is that it has lubricants and detergents that break down over time and need to be refreshed.
This is the main reason you don't change the fluid in a trans that is damaged.
The new detergents can finish it off in a hurry.

If making adjustments, the fluid is nice and red and clean and the pan has to come off one or two more times, then I use the same fluid again.