You... do not
need to do
that for Optimal Drift anyways...
Admittedly, the image overcomplicates this. You're just trying, ultimately, to meet four guidelines simultaneously:
- "Get near maximal (GCD) potency under each RoF",
- "Don't delay RoF unless it would allow for an extra Leaden or Demo under RoF, and by no more than a GCD",
- "Don't let Demo or Twin fall off", and
- "Don't clip Demo by more than a single tick per minute."
The "Drift" part just notes that (at the BiS GCD speed) you're not going to start each RoF on the same GCD. Instead, optimally, it will... drift.
Tbf, though, if you increase your SkS quite a bit further, you can meet those criteria without actually having to shift things around. You just end up doing Opo->Twin->PB->RoF->Opo->Opo->Opo->Phantom->Demolish->Opo instead for your odd-minute bursts instead while every even minute runs from Demolish to Demolish and ends in Phoenix (and, with enough speed, a final Leaden falls under RoF).
But... Crit is king for a reason, so the max damage from that rotation is faintly less. If you like being a speed demon and dislike having much drift, though, you may as well go for that.