Label instructions for Apistan state 1 strip for every 5 frames that are
occupied by the bees.  This is a bit grey.  On a warm day (not too many
of those left) bees in my hives will occupy all frames in both hive
bodies.  However, when the bees are clustered there are some frames that
aren't occupied.  Furthermore, I have no idea on which frames the bees
will cluster when the strips are in the hives.  In other words, guess.
Take a swag (scientific wild ass guess) where the bees will cluster.  In
most of my colonies I used 3 strips, two in the bottom box symmetrically
centered three frames in from each side and one in the top box usually
between the middle frames.  My swag is based on the assumption that for
the period that the strips are in, my bees will cluster more or less
symmetrically in the center of the space inside of a double brood
chamber hive and the cluster size will approximate the size of a
basketball.  If my bees swag differently then I will have less than
optimal placement, but the world won't come to an end.
 
Regarding leaving the strips in until spring, it's counter to label
instructions, which I guess is a violation of the law and makes "strip
leavers" criminals (requesting Pollinator's response to this statement).
It is also suggested that such misuse of the product can lead to Apistan
resistance.  I have heard confessions from mentoring beekeepers speaking
to my beekeeping association that they have left strips in their hives
because they found it too inconvenient to take them out in early/mid
winter.  As far as breaking the cluster, you should be able to get the
hive open and strips out quickly enough that the impact will be minimal
if not negligible.
 
This is not a criticism directed at Rett, but I am always amazed when
people read the product label instructions and they turn around and ask
if they can use the product in a manner inconsistent with the label.
The answer is yes you can, but every action has it's consequences.
Again the world won't end, but there is a price.  Perhaps the price is
you have fluvalinate build up in your brood combs.  Perhaps the price is
varroa becomes resistant to Apistan.  Perhaps the price is you feel a
little guilty and nothing more.  But the label instructions state what
they state.  Anything outside of what is stated is a misuse of the
product, period.
 
Aaron Morris - I think, therefore I bee!