Far from perfect but sucking out as much as you can with a topsider then replacing the extracted fluid helps.

Do this every oil change & over time you will replace the fluid. Remember that with modern synthetic fluids unless you have really cooked the base oil it is the additives you really need to replace. But if you want to keep the vehicle for the long run best to do it properly.

Simple flushing can be a horror. So a flush should only be done AFTER dropping the pan, extracting the crud and changing filter. How many shops do that?

Sealed for life? They never said whose life.