One of my observations on optical media when testing with a heavily scratched audio CD:
Multiple optical drives I have tested read damaged audio CDs fine at high speeds, but at lower speeds, they get stuck (making hiccup sounds once per second).
Shouldn’t reading be more reliable at lower speeds? So how come the drives get stuck at lower speeds, but just gracefully read through the damage at higher speeds?
What is the technical reason for this behaviour?
On an old GDR-8162B, I have turned the potentiometer down (reduced laser power), which actually improved readability on damaged CDs (although making CD-RW undetectable). This must be a related technical reason.