You can improve realism by setting realistic minimum healing times
This website details approximate healing times for various common sporting injuries, including things like various broken bones, bruises and lacerations. It's not in particularly great detail, but should give you a ballpark.
I'm not familiar with the reliability of the website, but where they're stated they tally with advice from the NHS which is trustworthy. It should be noted though that they average a little on the low side, so take them as rough times for a best-case scenario. If anyone's healing significantly quicker than this then you might want to think about explanations. As others mention, there can be many other complications:
- Age, other illnesses, amount of food available and general fitness will affect how fast something heals. The worse the situation, the longer it will take. Some other injuries will prevent things healing entirely (e.g. heart attack resulting in reduced bloodflow to the lower body will inhibit healing).
- The wound will need to be clean and infection free. Depending on your time period this may be more through luck than judgement. If it isn't, it could take a lot longer and/or not heal.
- The wound will need to not be very complex. If it would require surgery today to fix, it's likely that it wouldn't be fixable with pre-modern medicine. You'll either end up with something healed incorrectly, not really healed at all, or amputated.
- The wounded person will need to not do any more damage to the injury. This is an issue even today when we know about this as injuries typically feel ok to use well before they're fully healed. They will likely have more pressures on them to use whatever's injured than we do nowadays.
- Linked to the above, it will take a lot longer after an injury's healed to get even near the strength you had to begin with. Even with modern understanding of physio, it can take longer than the healing process to regain strength after a serious injury. After healing the wounded body part will be usable, but it will take more time before it's 100% (or could never quite reach 100% again which is more likely for serious injuries).