Why do we cast Verthunder twice?
Casting Verthunder twice is intentional as it allows us to guarantee a proc from Verholy as we will have lower white mana when we use it, resulting in us having both procs after our melee combo. You can also do this in the reverse order, casting Veraero twice and then Verflare.
Why are we potting a GCD later than usual?
Potting after the 2nd GCD allows us to use both Swiftcast and Acceleration after the first GCD, beginning the cooldown of both of those abilities and allowing us to comfortably weave our potion, Manafication, and Embolden in the next 2 GCDs. This also allows us to get our second Fleche under potion.
Why are Fleche and Contre Sixte used so late?
Using Fleche a few GCDs later than usual will usually not cost a use. As this is a general-purpose opener, if there are fights in a given tier where phasing causes you to want to use Fleche or Contre Sixte earlier, fight-specific openers will be made and posted along with fight-specific tips.