I've not read anything about this anywhere, but I have done a fair amount of
underwater photography and videography for myself. The obvious and likely
best answer is to remove them from the housing. When no forces are applied
to an o-ring it would make sense that it is likely to survive longer.
Provided you clean the o-ring groove well before replacement I can't see a
better way.

Bear in mind also that if you travel by plane with your housing it is best
to remove the o-ring. If you close the housing with o-ring in place, then
fly, you should have problems opening it at the other end due to the
pressure changes that have occurred. If you don't have problems opeing it
then you should start worrying about the integrity of the housing and/or
o-ring! So... before flying remove the o-ring, then you can usually close
the housing safely and open again at the other end fine.

Stan

What camera housing?

Take the O-ring out if it will be stored for a "long" period of time,
more than a month or so.  O-rings can take a set if kept under load for
a long time.  Your definition of long time may vary.