This summer I've had a problem with cooks overcooking meat and fish. Actually, one in particular. After spending time with him in the kitchen I understood that part of the reason is that he likes his own food well done. The GM, who also likes things well done, suggested printing pictures. So I found some decent pictures of steak cross sections, along with temperatures, which seem to have worked out.
The fish is another problem. I just have to keep working with this person, telling him "We can always cook it more, never less." It's tough for him I know, because I also am adamant that the food come up quickly when it's been fired, so timing can be difficult.
Training and motivating staff is one of the biggest issues most restaurants, particularly those outside of metropolitan areas face. Once you get out of the city, finding kitchen staff that actually are interested in cooking is difficult. Most kitchens are staffed by people who, while they might have achieved some technical proficiency because they have done it long enough, don't have the spark of a committed cook. I suppose most businesses period, are staffed by people who are working only because they have to, and while they might be decent at their job, don't have a real passion for what they're doing.