I think it keeps going on... never heard of cap
First of, the possibility of a cap was discussed in this very forum before, that wouldn't be a completely new concept when it comes to artifacts. And secondly, so you would argue that a 160% Triple Strike (totally fictional numbers, I wasn't willing to look them up, so this number is just for the following argument) would mean that not only any territory would be free, but in addition you would effectively get an Army Cache worth 60% of the army requirement on the captured territory? Sure, you can only activate this artifact once every 16h and only if you already own three neighboring territories, but even then, to me this seems ridiculous.