Why do some coil binding machines punch oval holes and some punch round holes?

Both oval and round holes use a 4:1 pitch, but the oval holes allow you to have 44 evenly-centered holes on an 11sheet, they allow easier page turning, and also allow the coil to be inserted more easily. Standard 4:1 pitch coil can be used with both types of holes. While oval holes may increase productivity by up to 40%, they aren’t as common as round holes.