Transmission fluid drained twice during change?

[JV06]

Hey guys. Sorry if this has been covered, but I see where in the transmission fluid change instructions, it has you drain and fill the fluid for a second time after you let it idle and change through the gears... Just wondering why this is done and if it really needs to be done... The reason I'm asking is because I scheduled a transmission fluid change at the local dealership here and I'm over worried they aren't gonna do it right. Idk. Any information is appreciated. Thanks in advance.

[TrailBrake]

A quick and somewhat uneducated guess; the gear change is recommended to circulate the fluid throught the appropriate passage ways and to verify transmission function.

Also ensure the transmission filter is changed along with the fluid. This is very important.

[andreno]

Draining it twice won't cause any harm. It is recommended especially for cars with higher mileage.