If you have the option to use pressed media, you should choose it. Burned media is less stable over time due to a number of reasons, including the fact that the dyes used in the recording layer are organic and will degrade and deteriorate over time. The amount of time this takes depends on the quality of the original blanks, the manner in which they are stored and how well the discs match the firmware of the drives used to burn the information.
So it should be apparent that there are many different variables involved, and I haven't even mentioned burn speed issues, deterioration of the reflective layer or problems that arise from physical flaws on the discs, such as dust, fingerprints or poorly spread dye layers.
Add to this, we have the slow loss of good quality suppliers for blank optical discs. Taiyo Yuden was one of the most reliable for both CD's and DVD's, but they are no longer producing optical media of any kind. This leaves DVD media from Verbatim using the AZO dyes, but even discs with AZO on the label may not carry the Mitsubishi MID codes any longer. I'm not sure who makes the most reliable CD's these days.