From Project: Redcap
The length of time required to recover from a wound depends on the severity of the wound. After a certain amount of time has passed, the character generates a Recovery Total. Depending on the outcome of this Recovery Total, the character's wound(s) may improve one step, stay the same, or become worse! (presumably due to infection or complications).
The length of time between Recovery rolls, the formula for the Recovery Total, and the Ease Factor to avoid infection are all given on page 179 of ArM5. Factors affecting the recovery total include the caregiver's score in the Chirurgy or Medicine Ability, the patient's Stamina, and Creo Corpus magic (or Creo Animal if the patient is an animal). Note that, as stated in the second-to-last paragraph on page 179 of ArM5, Wound Penalties do not apply to Recovery Totals.
The mechanics of recovery imply that a skilled physician (5 in the Ability) would be able to heal Light or Medium wounds fairly regularly, for most patients. Healing Heavy or Incapacitating wounds requires more extreme levels of skill. Magic - especially magic items - are often used in sagas to facilitate recovery, however, and can easily allow even incapacitating wounds to recover quite reliably, even without a skilled physician.
Magic can also be used to directly heal the wounds, but effective healing requires Ritual spells and hence raw vis. In vis-rich sagas, magi will likely use raw vis to heal all but superficial wounds, greatly speeding-up and increasing the odds of recovery. This means that the recovery mechanics would largely be used only for background or unimportant characters. In vis-poor sagas, even serious wounds would likely be addressed by medical care.
Note that Divine magic can also heal or speed up recovery, and would be often invoked in the setting to do so, although actual miracle-workers and supernatural healing may be rare. Meditation Blessing spells can easily help with recovery, while powerful Purity Intervention miraculous effects can directly heal wounds. Certain saints, angels, and Divine beasts also have healing powers, and medieval legends are full of stories of healing locales and relics. Depending on the availability of such sources of healing, recovering from wounds and disease in Mythic Europe might be a considerably lighter burden than in historical Europe. (See Realms of Power: The Divine for rules on all these sources of healing.)
- ArM5 page 179