Rinsing and Twintubs
My take and experience...
In my Hoover machines, I usually open up the pump and find horrible crap (detergent residue) in them and it has usually gone terminal and destroyed the pump. With a lot of these small machines, they were usually oversudsed and never rinsed out. With a Hoover especially, you use the spinner to rinse and the last thing the pump sees in a use is the mucky, soapy water being drained and then the machine being put away. Few people ever flushed the pumps with clean water. One machine that I have been using on and off for 4 years now was like that when I got it. I replaced the pump with a good used one that I had and lubed it up. 4 years later I disassembled it to lube the bearing and found NOTHING in the pump. As clean as it was when I assembled it. I attribute that to clearing the pump after use.
Now for the double rinse theory that Tom has, I do understand that. If heavy soap was used in the wash and not rinsed in the first rinse, then I see no harm that could be done by flushing away more of the soap residue. I suppose that this would depend on additives and the hardness of the water. Again I can see that if ample amounts of detergent was used. I don't find Maytags to be exceptional rinsers with the "recommended" amount of Tide or Gain in them and I too will dial in a 2nd rinse at times. The GE-FF never needs more than one rinse and recently when pulling the tub for inspection was relieved to find no buildup. All of these machines see hot water washes and bleach regularly. I like to rinse and see the water as close to clear as possible, and so far this does not seem to have been detrimental to any of my equipment.
-Tim