B · Engine & Sequencing · §7
What triggers what, in the order the game actually checks it.
Three separate things care about how many spells you cast, and they do not all count the same way.
gets +1/+1 until end of turn on every noncreature spell. gets +2/+0. The Monk tokens the Cutter makes also have prowess. These trigger on every noncreature spell, with no limit per turn.
triggers on your second spell each turn, once. A third spell adds nothing to Flurry, though it still adds prowess triggers. This is the asymmetry that decides sequencing: the second spell is the valuable one, and spells beyond it are only valuable for their prowess and their effect.
surveils on every noncreature spell, which is how delirium arrives without spending a card on it.