The cast of My Hero Academia have many lessons to learn. The likes of Shota Aizawa/Eraserhead and the experienced Gran Torino are excellent teachers. For Tenya Iida, however, there some lessons that no pro hero can teach him, and that he must learn through experience.
Tenya Iida is the class representative of class 1-A at U.A. He's doing his very best to live up to his responsibilities, from his studious ways to his eagerness to be a coach for his classmates and his dedication to becoming a great runner hero. However, just because he can run fast, doesn't mean he should rush through the steps to become a hero. Otherwise, he might slip and fall into villainy, or totally lose his way.
The Frustrated Leader
Tenya Iida is one of the most ambitious students in U.A. aside from Izuku Midoriya and Katsuki Bakugo. His personal role mode is his big brother Tensei Iida. Tensei is the runner hero known as Ingenium, and Tenya is a little too eager to live up to his brother's reputation immediately. To that end, Tenya pushes himself hard to succeed and to prove himself to others, in ways ranging from his deeply studious ways to his stern discipline in the classroom. He earned his way toward becoming class president, and in that capacity, he knows what he's doing, but he is getting ahead of himself. Iida seems to fancy himself a teacher, scolding his classmates for small infractions and taking himself rather seriously. For the most part, it's played off as comic relief, but no doubt Iida is feeling frustrated in his role. Why won't his classmates listen, and why aren't they taking this more seriously?
Iida had moment of glory when he acted as a swim coach for his classmates during a break from class, but otherwise, he's setting himself up for endless frustration. It takes time for a great leader to establish themselves and earn respect and trust. Iida needs to have faith that someday, when the time is right, he will be a class rep that everyone, even Bakugo, can look up to. Otherwise, he may wind himself too tight and end up snapping. Unless he's careful, this trend could potentially lead to arrogance, alienation or even the temptation to seize quick and convenient power to force his classmates to respect him. These two paths are mirrored in One For All and All For One, where the bearer of One For All patiently and diligently trains to earn their strength while the bearer of All For One can just steal other people's Quirks to gain easy power. Iida must make sure that he does not become a mental All For One, and instead assume a career path that mimics One For All.
A Hero Too Soon
This impatient drive to become a perfect hero made itself clear when Tensei Iida was ambushed and nearly killed by Stain, the infamous hero killer. Tenya had every right to be concerned for his brother and feel terrible about Tensei's early retirement, but otherwise, Tenya's reaction demonstrated reckless thinking driven by impatience and an excessive need to prove oneself. Tenya Iida burned for revenge, and he was already frustrated at his slow progress at U.A. If he couldn't even avenge his brother, he reasoned, he was no hero at all. He had nothing to show for it.
Except he did. Tenya Iida was class rep at the country's top school's top class, and he was slowly and steadily improving as a hero, right alongside his classmates. Izuku, Ochaco, Rikido Sato and others were making slow but steady gains, and Iida felt the need to race ahead of the pack. And it cost him. He very nearly lost his life to Stain, and he was left humbled and shaken after he was rescued by his classmates and the battle against Stain and the Nomus wrapped up. He had tried to jump ahead nad do everything at once before he was ready, and he had little to show for it except a brush with death. So far, four seasons into the anime, Tenya seems to have learned this lesson well, and he is sticking to the "slow and steady wins the race" path with his classmates. It can only be hoped he stays on that path and resists all temptations to the dark side, where power comes easily but at a price.