Two.
Most of the "classic" writing schemes have been developed for ease of communication IMO.
When I put two spaces in my stuff, I mean two spaces, and software that eliminates one of them is, well... not quite an abomination in the Biblical sense, but it is a mite offensive.
Besides, that's the way I learned it in touch typing class in 1953. So there. :neener:
Poerty? Well, that's another matter and depends on how a poem means.
tyRRX