Richard
All our work is military based and we frequently use components older
than 5 years. They are generally stored in ambient conditions and well
packaged. We do not periodically bake there is no benefit to be gained
and it could exacerbate the solderability problem. We would only bake
prior to assembly/soldering operations. However, we do on occasions have
to store a one time buy of components which are likely to become
obsolete. These could be stored for 10 - 20 years and is done in white
spot nitrogen ( dry ), so far this has been satisfactory.  

We do solderability tests every 2 years to evaluate components and in
all the years I've been doing this I've only seen problems with Sn/Pb
finish after about 6 years old. I've never seen a problem with gold
finish components for solderability due to storage. (I just hope that
continues now!!! :)

Regards
Chris Evans
MBD UK