A Samurai confused about Hagakure usage

[Gr1mwolf]

Another point of confusion I've seen argued a lot is whether Hagakure should always be used immediately with at least 1 Sen, or wait until you build 3 Sen.
If we say that Hagakure is worth 720p every 40s when used on cooldown with 3 Sen, that would be 18 DPS.
Let's give the most extreme case, and say the cooldown comes up when you have 1 Sen from Yukikaze, and no Skill Speed.
You should always have Shifu, putting you at 2.25s recast.
It would take 13.5 seconds (2.25x6) to get up to 3 Sen, costing 243p (13.5x18) compared to if you already had 3 Sen.
If you used Hagakure at 1 Sen, it would have had 240p. A net loss of only 3 potency in THE most extreme case.
Let's be more reasonable, and say that you have 2 Sen, and can use Yukikaze.
It would take 4.5 seconds (2.25x2) to reach 3 Sen, costing 81p (4.5x18), but with a gain of 240p on Hagakure. A net gain of 159p.

Even a tiny amount of Skill Speed should cause them to break even on the worst case.
Mathematically, you should always build 3. Does this look right?