For the curious

Out of curiousity, last night I ordered two identical items on Amazon. On one, I took the free 'Super Saver' shipping. On the other, I paid $4 for regular shipping. The orders were made five minutes apart.

Tonight, about 24 hours later, I received two shipping confirmations for the items. About five minutes apart.

Around holidays, or when time is critical, go for the more expensive shipping if you're worried, but I'm pretty sure that the time estimates they give are just to encourage you to pay more.