Sorry Jesterrace (Hi ), but this is IMO just as incorrect as saying the opposite, "the slower the better" (which is just a myth with absolutely no sound background, unless one goes back to the time of 4X-8X rated CDRs and the burners at that time).
Whatever the media, there is always a speed at which it gives, in a given drive/firmware, its best results. It's never the maximum speed in my experience (nor is it the slowest speed). Most modern CDRs (40X to 52X rated) are at their best when burned around 24X-32X, and if jitter is considered as important, around 12X-24X.
Where I agree with you, though, is that for most users, these considerations are useless. Premium Verbatim CDRs (just an example) burnt at max speed give most satisfying results.
@the original poster: lots of guys will give you such advice as your friends', though they generally don't know what they're talking about, and are just repeating something another friend told them (or that they've read around the net). The truth is that the lifespan of a disc has much more to do with its inherent quality (use premium discs), the storing and the handling, than with the burning speed. There is actually a kernel of truth in it, as higher burning speeds produce more jitter, something that could (could) impact the dye's structure stability, but nowadays with most (good) burners and (good) media, actual jitter is not higher @24X burning than @2X burning.
If you really want to be on the safe side, burn good discs (with Taiyo Yuden, MCC or Maxell mediacodes) @16X-@24X in a good CDR burner (Plextor, NEC, LG) and you're good.