The 95 focus is the point of no-capping focus not the focus you should pool before apply vulnerable(MS or WB).
You should apply vulnerable whenever its available and you are not inside a vulnerable window.
The guide is explained as an APL so lets see if I can add another perspective explaining it as a event-based rotation.
1.You AS till 95 and then AiS to not cap focus.
This "rotation" stops at a MT proc or WB becomes available.
MT Proc
1.AS (or MS at multitarget)
2.MS.
3.AS.
The 4th step is the key here and the real decision in the rotation.
Are you gonna have enough focus to cast 2 AiS inside this Window?
4.1.NO -> As
4.2.YES -> Ais
5.Ais
Now,its not like we are losing focus for casting just 1 Ais inside the window.The focus you havent used by casting AS instead of Ais in point 4 is going to be available for the next vulnerable window so in the end we alternate between two rotations in the MT event (based on how much focus we have at the MT proc).
"Bad Event" (not enough focus)
AS(or Multi) ->MS -> AS -> AS ->Ais
"Good Event"
AS(or Multi) -> MS ->As -> Ais ->Ais
WB available
Almost exactly the same as the MT proc but given travel time and distance you are going to be able (many times) to fit 2 AS before the first Ais so
"Bad WB"
WB -> As ->As-> *As -> Ais
"Good WB"
WB -> As -> As->*Ais ->Ais
(*) Am i gonna have enough focus to cast 2 Ais before the window end?
As we can see the rotation is just choosing(based on focus) if we end the window with As+Ais or 2xAis although theres (of course) exceptions: under high haste procs or at focus cap you try to fit 3xAis inside the Window.
I hope this clarifies the rotation ( and hope too Im understanding it right
lol).