The word count may corresponds to fewer or more bytes than that are contained in a sector. When the data block is longer than a track:

The disk address register is incremented as successive sectors are read or written. When one track is completed then the surface count is incremented by 1.

Thus, long data blocks are laid out on cylinder surfaces as opposed to being laid out on successive tracks of a single disk surface.

This is efficient for moving head systems, because successive sector areas of data storage on the disk can be accessed by electrically switching from one Read/Write head to the next rather than by mechanically moving the arm from track to track.