The correct answer was already there and the point you’ve tried to make ignores the reason why PoM is left till the end of AP.
Your logic would require an exact amount of haste for the gcd and cast time windows to line up and for you to know that exact amount of haste and thats not including random haste buffs.
Have a look at the diagram on the altered time discord. If you still think it’s wrong take it up with the world class mages on the discord.