the only information on freezing films accompanied with figures I know of is this information from Agfa on a current B&W IR of their make concerning latent image stability. If you should be able to read those figures you will understand that you are on the right sight when employing freezing (concluding on unexposed film):
Average gradient drift based on a a gradient of 0.9
1 day 1 week 2 weeks 3 weeks 4 weeks 5 weeks
Shelf -0.02 0 0.04 0.04 0.04 0.04
Fridge -0.01 0 0.02 0.02 0.03 0.03
Freezer -0.03 -0.03 -0.01 0 0.01 0.01
The expiry date is based on storage in the original packing and at an ambient temperature of 8°C. Colder storage expands the life time of the product. Ageing of the film is very limited when the film is stored in the freezer.
(Sorry for the bad readibility. But uploading spoiled my formating; sort it out yourself...)