I believe it is documented: Deck Options - Anki Manual. The preset does apply to every deck using that preset. But presets control the limits, not how many cards have been done in that branch of the tree. As you said, if you’d like to impose a global limit on the number of reviews, you need to put all cards under a single top-level deck, and click on that deck, or keep an eye on its remaining count as you click on subdecks.