Don't ever, never take your car to jiffy lube or any of those places.
When ya drain the oil, leave the drain plug out for 15 or 20 minutes. I leave my out for 2 hours. You have to allow all the dirty oil to drain out that is clinging to all the internal engine parts..
If ya don't do this, your putting new oil in with old nasty dirty oil.
If ya like your vehicle, and want it to last, do this.
Right you are about that! My late dad always let the oil drip out of the engine for at least 2-3 hours before adding new oil to the engine. That is how you do the job right!
Dad was right, but this has more to do with engines than transmissions. But transmissions should also be allowed to drain out for at least 20 minutes.
BTW, I sometimes allow my engine oil to drain completely over night before adding new, when I know I wont be using my vehicle over night.
I run the recommended dose of Sea Foam through the engine on the Toyota for 30 minutes before hitting the dealer for the oil change. The oil coming out looked black from the upper block deposits it scavanged.