The two previous posts (First, Second) discussed the unwise practice of bare knuckle punching of bony areas like the head. As such, when considering self-defense we should train open hand techniques for attacks to the face and skull. However, this may present a problem for your school or for you personally.
People come to a martial arts facility for a variety of reasons, including fitness, wellness, confidence, self-centering, but it is fair to say self-defense is always included.
However, some folk will attend such an institution to prepare for entrance into the ring or cage. This presents a problem when dealing with the self-defense aspect of using open hand techniques on the head. In sport where gloves are worn, punching the head is the norm. Moreover, open hand techniques to the head may result in disqualification during a contest.
If the classes you are involved in are mixed, ring folk and the never-going-there folk, you have a problem. How do you condition the self-defense crowd to refrain from punching the head, while conditioning the ring group to use only punches?
Honestly, you cannot. The best you can hope for is that you have even numbers, and you can isolate techniques and combinations to each group. When the numbers are not even, forcing a self-defense person to be paired with a ring person, woe will result as each corrupts the habits of the other.
In all seriousness, the only way to insure these two groups build their specific necessary attributes is to isolate the classes, with no crossovers. The individuals wanting to do both will have to take some time at their personal reflecting pools to determine what they truly desire. If their sights are set on the ring, they need to focus on that until those goals are met or set aside. They will still be in a better self-defense position than the inexperienced person. However, you do not want ring habits to infect self-defense and vice versa.
As the previous posts discussed, it is too easy to fall into the habit of punching, even when we should not. However, sport requires it. It can be argued sport too easily corrupts self-defense. Punching is a social meme. Likewise, pure self-defense training would destroy a ring fighter.
Some martial artists may have a hard choice to make.
Meet the challenge. Guide it away. Move forward into the opening.