Who you agree with more? Kollontai's Glass of Water theory or Zalkind's Twelve Sexual Commandments of the Revolutionary Proletariat? Were they good for 1920s-1930s Soviet Union? What about current implementations, which one would you lean closer to and why?
Apparently Kollontai didn't develop the Glass of Water theory. I don't know how true that is, since I've never even heard of Kollontai until I read your post, but this article is an interesting read nonetheless: https://www.marxists.org/history/etol/newspape/atc/1724.html
For what it's worth, Lenin calls the "Glass of Water" theory "completely un-Marxist": https://www.marxists.org/archive/zetkin/1920/lenin/zetkin1.htm
I think he comes off as a bit of a prude in this. Maybe Kollontai sometimes goes a little too far but on the whole I think she has a much more progressive position on the topic of sex than Lenin does.