On the topic of the necessity of a DC, I have a story that happened to me. I had not begun doing internet exchanges until summer of '08. Since then I have had smooth trades and sales. Then in last December, I had a nonknife related trade on another forum. The deal was that I would send my item out first because I had less reference than he other person. So I sent it out, but for whatever the reason was at the time, I didn't get a DC. A few weeks later, the receiver PMs me telling me that nothing has arrived. Since I had no proof that I had sent his stuff out, there as no way to convince him that I sent his stuff out. At this point, a mod had been notified of what happened. I insisted that he kept his end of the trade so he would not be losing anything. Well needless to say, because of this whole ordeal, I am now in a one year ban from exchanges on that forum.
I always use DC and request it to avoid another siuation like this. No, I don't have time to sit around all day with UPS or Fedex or USPS website open to track my incoming goods every minute of the day. I might check them every nce in a while, especially if I am exited about what is coming. The point of the DC to me is to avoid disputes such as the one I had. If I claim to have sent something to them, andthey claim that they didn't get it, I can have some evidence to protect myself with. And vice versa, if I have the DC of something that is to be sent to me, I can at least look into the other possibilities of wrong address delivery (this has happened to me) or something else.
That's my view on tracking numbers.