The Messy Reality
…Of Not Knowing How Bad It Is
Most harm during a fight is a mix of real injury and temporary shock. You won't know how badly you're actually hurt until the adrenaline wears off.
Smart GMs call for a recovery roll soon after a conflict, once characters have had a chance to breathe and bind their wounds, maybe eat or even sleep. Any Harm that disappears was just Complications like temporary stunning and pain. Whatever remains is real Injury that needs time to heal. (Any actual Injury there from before can't be healed this way.)
This means it's better to describe Harm as "stunned and bleeding" rather than "gaping chest wound." Let the post-fight recovery roll reveal how much was just shock and how much was real damage. Again, you can tune your game by deciding whether to include Harm penalties in this roll; for new damage, the default is to assume it's all Injury until you know otherwise, but if you want your heroes to walk it off more easily, don't include unclassified Harm.
If it doesn't make sense for an Injury to impede the character for ongoing rolls, perhaps it should have been treated as explicit Complication, but instead of designating it as Injury, the GM may also convert it to a temporary Hook. This allows it to be applied thematically, to alter the character's motivations, but to be normally Recoverable.