That method MIGHT work, But, it depends on how the transmission is programmed for the torque converter and how much it allows slipping to occur (which is heating up the fluid btw). See, the heat from a transmission isn't just generated like heat in an engine. The transmission is heating up from "losses" in power. Say for example your engine is putting out 220hp at 4,000rpm, That would be the power delivery to the transmission. The transmission then must use that power and transfer it as efficiently as possible to the rear axle and front axles. Any losses of power turn into "heat" and that heat is what we see as overheating in a transmission. So, it's up to the transmission heat exchanging circuit (see it's a heater and cooler remember) to transfer any excesses out of the circuit. So, if for example a well designed transmission circuit flows at a normal rate of 4 gallons per minute. If there end up being restrictions in the lines and other manufactured parts then you'll only get 3 gallons per minute for example. So, on a "clean" well designed and manufactured setup you get full flow of the 4. But others only get something less. And that something less can allow heat build up to occur in places that the transmission doesn't like. For example the torque converter. If it gets too hot then the torque converter plates will get excessive wear and the metal will "blue" out showing the excessive heat in the converter. I've seen all of this occur and when you see a blued converter it's easy to see it was overheated. The purpose of the fluid is to transfer efficiently that heat out of the units. If the fluid itself is compromised (black usually) then it's in a "burnt" category and isn't going to do the job anymore. Eventually the transmission plates and clutches burn up and the thing is shot. See, that's the importance of monitoring trans temps and even an occasional fluid smell and "feel" test. It's easy to feel the grittiness and see and smell the burning fluid (it smells like burned resistors). Monitor the situation and help yourself is my motto. Change the fluid regularly (30k is a good number unless towing more and heavier and I'd go to 15k) and also while taking fluid out send a sample for testing. That way you know where you stand at any point in time. I did mine at 30k. I'm monitoring the fluid color for now and have plans for the next fluid change at 60k (in 18k miles). Time will tell if I get this right. But knowing about fluid and transmissions I'm hoping my experience pays off in the long term.
Steve