Fast Healing in combat

[Hallack]

Wither from Vigor or other means how many here use Fast healing for healing during combat?

Mostly I ask because this past weekend my group for whatever reason ended up reviewing the Fast Healing rules (thought we had them down) and discovered we've been doing it wrong for years.  We'd been letting Fast healing function in combat, mostly only an issue with tricks like Persisted Mass Vigor but still.

Fast healing doesn't work in Combat or similar strenuous activities.

[Empirate]

[Shiki]

It'd seem pretty counterintuitive if it didn't work in combat. That's like, the whole point of the ability, like Regeneration.