Need to build some systems this week. Snapshots?

[Colin Percival]

At 22:49 30/08/2003 -0700, Wes Peters wrote:
>Now, if you want to discuss a way for the ports builders to say "Wow,
>that seemed like a pretty good one!" when bento builds somewhere north
>of 90% of the packages, so they push a button and produce a snapshot,
>that's a least a possibility.  That will never handle the awful morass
>of dependencies on complicated packages like GNOME or KDE applications,
>but it MIGHT produce occasional snapshots of some use to some people.

   Can someone explain to me why it would be necessary to build *snapshots* 
of the ports tree?  Why can't packages just be rebuilt when they change -- 
the way portupgrade does?
   I get the feeling that I'm missing something obvious here...

Colin Percival