So after over 900 days of in-game time, my stats look like this.
The reason is that on each slave I can raise the medic skill exactly twice: when training the nursing skill from F- to D- and when training from D- to C-. So the medic skill, which has about the same limits as other skills, but is only upgraded by teaching one skill, seems somehow wrong. Other skills that are associated with only one or two slave skills (Fighting, Magic) have alternative ways of leveling up to S+. The medic skill also needs similar methods, for example, gradual pumping during the treatment of bruises or wounds.
The reason is that on each slave I can raise the medic skill exactly twice: when training the nursing skill from F- to D- and when training from D- to C-. So the medic skill, which has about the same limits as other skills, but is only upgraded by teaching one skill, seems somehow wrong. Other skills that are associated with only one or two slave skills (Fighting, Magic) have alternative ways of leveling up to S+. The medic skill also needs similar methods, for example, gradual pumping during the treatment of bruises or wounds.