the modern automatic transmission is made of a labyrinth of valves and tubes. and these are oiled in from manufacturing.

when we do normal atf change, these valves are not disturbed hence not having problems and it's very small tubes, if there are sediments caught in it ur transmission would have failed already. So just doing the normal filter change is valid.

Not saying total ATF flush is bad, but you really do have to get someone that has a really good machine that is assured to replace the atf by balancing the input and output flow to not affect the valves. But as everyone puts it here, it's a risk to actually find someone that can be assured to do that.

Choice is still up to you. Information has been given. Choose wisely.