Obviously, the biggest impact on a set's year designation is the status of RCs. Since ITG products are unlicensed and do not have any rookie cards, that part of it is irrelevant to the discussion.
The second biggest issue, though, is how accurate the set's year designation actually matches up with when the product was released. In that aspect, for example, releasing a 2008-09 product two months into the 2009-10 season pretty much doesn't make any sense at all.
ITG Ultimate doesn't need a "hockey season" designation. It's not a set that ties itself to a specific season of current hockey anyway. ITG would be best served to officially name the set with the calendar year it came out -- for example, this November's release would be 2010 ITG Ultimate 10th Edition.