CLV instead of CAV I
Data on a CD-ROM is stored in a single, spiral track. This allows the data to be packed as tightly as possible since all the sectors have the same size (whether in the center or at the edge).
In the “regular arrangement”, the data is packed more densely in the center than in the edge ==> Space is lost in the edge.
Since reading the data requires that it passes under the optical pick-up device at a constant rate, the disc has to spin more slowly when reading the outer edges than when reading towards the center.