See my other post for more details

Most modern media is optimised for 8x writing, as most writers being used are that speed. That means that they will write reliably up to twice that amount, ie 16-speed. Audio only disks are typically using the same dye formulation as was used when discs were optimised for 4-speed. But in any case, all these discs should work at 1-speed or 8-speed. At 12x and above the audio discs are well out of spec, although some manufacturers now are simply putting the extra info on stock 16x-rated (8x-optimised) media as it rarely causes problems. You can't stress a blank disk by writing on it, not unless it's really cheap (I have seen some CMC disks which look like the top surface has been affected by a burn, but they still work OK).