Using the spouts that come on gear lube bottles makes a mess and takes for ever, at least it does for me. Auto parts stores usually carry a different spout with a twist on/off and plastic tube attached. Don't use the tube, just the spout. I can empty a bottle in 10 seconds with this, and no drips since I can turn off the flow. Just thought I'd share.
A little off topic... I work in a shop and have to fill transfer cases/standard trannys/auto trannys w/o dipsticks with atf quite often.
I have an old 1 gallon pump up sprayer. Like the ones for spraying insecticide. It actually was free with a gallon of Castrol Super Clean. Pumps 3 quarts of atf in 30 seconds. Just don't fill to the top or you have to pump more air into it before running dry.