I thought 16 2/3 RPM was for spoken word recordings. You could get twice as much stuff on a record and didn't need the dynamic range and band width. Bass whacks take up big groove space. Because it was spoken word, it didn't take up much groove space. I never heard of music being recorded on 16 and 2/3 RPM in North America, any EP's I had were at 45 RPM too.