Website Update Delays?

I've made updates to websites and had it take several days
to show up in a browser. I've used websites that had some
kind of "staging area" that was used to test updates that didn't
get propagated to the public site for a day or so. I've
used sites where the administrator did this, and the delay
could be a few hours or minutes.

Recently, I was updating a site for a client who uses AOL,
and she didn't see the updates for days. I assumed it was
because of AOL's update/cache systems and many diverse servers.

Here's the part I'm curious about, though: I updated a site
on a Pair.com server, and the updates just would not show up.
I was using a powerbook running Safari. I cleared the cache,
restarted, logged out, waited several minutes, etc., etc., and
no updates. I tried this stuff because, as I said, I was curious
as to how long this might take and where the delay was. I ASSUMED
it was in my cache. Then I brought up Netscape, and the updates
were there. Okay, the cache was in Safari, but why didn't it clear?
And if there was some sort of non-disk (RAM) cache, why didn't the
logout take care of it?

Finally, the update for my client (this was last year) didn't show
up through AOL for three #*@(*$ days!

So - does Safari have some sort of odd cache mechanism that Netscape
doesn't have? Is AOL really as bad as ever, with it taking days to
propagate stuff through all their servers and filters and blockers
and stuff? And is cacheing generally limited to the local machine on
regular, old public ISP stuff (no censoring, blocking, cacheing?), but
still compounded by the immediate machine you're hooked to?

It sounds like I can no longer give a simple answer to my clients
about this, huh?

Comments?

Mark