the specs are all lies, time it with a stopwatch for yourself, I'd be interested to hear how close to the posted specs you get.
And if you add on the 'lead in', 'lead out/finishing' and for a laugh, mounting, verification and ejecting it gets even more silly.
Each of these bits doesn't take too long, but when you've been given the task of burning 200 dvds worth of data overnight, and you think that from the specs it wont be a problem, trust me, these little bits all add up!