Per the J-STD-033 and HIC manufactures, the HIC cards are pretty much usable indefinitely.  My experience is that the 5-10-60 cards are far more accurate and what is actually recommended by J-STD-033.  The 10-20-30-40-50-60 cards are not so accurate.
With the 5-10-60 cards, use on 5, bake on 10.  The 60 is for high humidity environments as anything above 60 RH is technically outside the scope of J-STD-033 for bake times.
Texas Instruments (TI) did a storage study many years back stating that in the bag life for solderability is 8+ years.
http://www.ti.com/lit/wp/slva304/slva304.pdf
As far as NADCAP, the life of the HIC is to be monitored and is 2 years or at opening.