I'm probably missing something but after every fight most if not all my team is wounded and it takes a lot of time (almost whole day) and medicine to heal. Every wound cost like 5 medicine and mercs have several of them, while you can find 2-4 medicine from 1 bush.
Next location has 14 enemies in a single squad, so it's safely to assume it will be another day and 60 medicine to heal everyone.