In general, I hate offer periods. I would much
prefer that someone just tell me what they want
for a cel or genga and be done with it. Guessing
games drive me UP THE WALL. This isn't the Price
Is Right, and I really have better things to do
with my time than play Blind Man's Bluff with a
monetary amount set in someone's else's head.

That being said, I can understand the occasional
need to get as much as possible out of the
collection when selling. There has even been one
emergency occasion in my past when I opened my own
gallery to offers. It was done for the same reason
that I think others sometimes request offers -- to
hopefully raise the needed money by selling as few
cels as possible. As someone has already said, you
never know what people are willing to pay. 

In my case, it worked -- I received one offer high
enough over what I had expected to save the other
cels I thought I would have to put up for sale at
set prices, and it happened quickly enough that I
did not have to play any back-and-forth games with
anyone. It still left a bad taste in my mouth,
however -- enough so that I don't think I could
ever bear to do an "offer" period again, no matter
the need for money.

I never did like Blind Man's Bluff, even if I'm
not the one with the blindfold.