Hi Tomturbomatic!!!!!
Answering your questions this washer is preset for 2 rinses in any cycle, you can only add an extra one but you can´t reduce to less than 2. I doesn´t fill with more water in the rinse than in the, but it does spin fast between all the rinses which make them extremely efficient.
I almost never add the other rinse cause for me 2 rinses are more than enough. Clothes have never come out with detergent, or sudsy, or as if they needed more rinsing, and because I use a "No rinse formula fabric Softener" this eliminates the need of extra rinses.
I just use it whenever I add Chlorine Bleach for example with the white towels. Whites don´t need bleach or chlorine, I just choose the Sanitize cycle with prewash and that´s more than enough. I haven´t need to wash my whites, eventhough I´m a Medical Doctor and need to be in white dressin daily, with Chlorine or in my Whirlpool since Samsung is here.
The silver wash option does make an excellent job in removing stains. So I don´t need anything else, beside Samsung, silver wash, Ariel with Bleach powder, Vanish Powder, and Suavitel with "No rinse formula", and this is my best cleaning team.
If you have any other question please let me know. I get really excited answering any your questions.!!!!!