Samurai rotation Hagakure or midare

[Bourne_Endeavor]

I thought Midare with some Kenki ready is a dps gain if you "squeeze the burst" into group buffs, outside of group buffs Hagakure is always a DPS gain. Correct me if I'm misguided please.

Far as I'm aware, you are correct. If party buffs are active and you won't be able to spam Shinten but can get a Midare off, the latter will be a DPS gain.

As far as pure potency goes I seem to remember that Hagakure is always a DPS gain no matter if you use it at 1, 2 or 3 sens, as long as you don't generate more than your 100 limit by using it.

Apparently, it isn't. You always want to build up to 3 Sens before using Hagakure unless you'll cap Kenki.