RC - What I was thinking was, how could anyone ever tell that there was no connection between roundhouses used by people who frequent boozers, and the same kind of people using boozers being referred to as rounders?

The only way would be if you could prove that the term rounders was used with this kind of meaning before the term roundhouse in this sort of context ever came along. Which of course might be possible.

"Rounders" as another term for people who keep on coming back for more bad treatment, recidivists maybe - that makes sense, even if it may turn out not to be etymologically the proven correct source of the word. Stuck in the daily round of life, even. Going round in circles, getting nowhere.

Maybe something like that lay behind the choice of Groundhog Day for the movie.

Words sometimes get reinforced by puns and suchlike adding a new layer of meaning to the initial one.. Like "Old Timer's Disease" for Altzheimer's. No connection with the original spource, but apt.