Everything I've ever read about silent films indicates that they were never projected at the same rate as they were filmed and that it's a modern convention that they be projected at a natural rate. There was never a standard speed, that much we do know. How it was presented was pretty much up to the projectionist. It seems that they were more interested in the picture ending on time than any sort of natural look. Also, the cue sheets tend to recommend the faster rates. None of them recommend the slowest 16 speed, since the film was too flamable for that. Audiences at the time were accustomed to the slightly stylized look of the projection, which looks silly to us, just as the acting does.

Oh well, this is an ongoing debate among the professionals and aficionados. We won't solve it here.