Many of them were probably used as Christmas tree ornaments. First, a little overview on how they work. The track is continuous and the process of burning the track is called a session. Because the laser burns through the bottom of the CD, a heavier plastic coating is used to seal and protect the burned composite on its bottom side after cooling.
Transfer rate is slow because of the thermal mechanical process.
CD-Rs differ from commercial CDs from the standpoint that commercial CDs are pressed from a mold and are a little more durable. Poor CD copies occurred for the most part on early machines due to a failure of the input data stream to keep up with the high, constant requirement of the recorders recording session. The small buffer size was insignificant with respect to smoothing out data losses. The laser must burn the disk at a certain rpm coupled with a certain laser intensity and data stream. Data flow must be continuous through the entire recording session since each recording session forms one continuous track.