I got a feeling his students are all op leaders as well...

Because although there's no face, the hairs have different styles and colors (means they're not unnamed characters)

I feel like I get what you’re trying to transmit with what you said, but unfortunately I don’t think that’s the case, this doesnt seem like the type of manhwa to be less detailed about characters that aren’t “important” just because they are not going to interfere directly on the story
For example, all the workers from the collection guild have different and detailed hairs and appearance traits, even though they are not going to be specifically important in the story