So back in the day I actually studied logistics. There is certainly nothing "intuitive" about it. And I mean nothing. How it gets to you is a complex and shouldn't be considered - I mean I ordered two things this weekend. One from Italy, and one from the States. I'll be getting my Package from Italy on Wednesday if tracking is to be believed, and the package from the states Friday. Not intuitive.
That said, how long it takes to get to you should be considered. If they say two days and you Pay on Monday - it should be at your place Wednesday.
When you pay for two day - it should be two day. It's a freaking contract for Pete's sake.