Your teacher probably knows more than you do. I have a friend who teaches a game art course, and every year the students complain about his harsh specs "That's not what people use in the games industry!" they cry.
It is.
He is probably trying to smack you around the head to make you think "Hmm...if I collapsed this vert and mirrored these UVs then....ah...and then...."
You need to remember that even though next gen consoles are powerful, their goal is not simply to display your artwork...and thus I present another of my rants:
Art for Games, not games for art.