The Athletic wrote a profile on Mitch Marner and how he became the player he is today not by chance, but because of carefully crafted training that started when he was four. This type of grooming of a player goes against what is known as Long-Term Athlete Development or LTAD for short.
The premise of LTAD is to acknowledge that all kids who play sports are not going to become stars and that retaining them to participate in sport for life is more important than turning out stars. Creating a love of activity is more important than creating those star athletes. LTAD also acknowledges that as athletes get older, some will become elite and there is a specific path that they follow that ensures they get the training and support they need. More importantly, it is acknowledged that there are fewer elite athletes and their needs are met as well.
That said, one of the takeaways from the Marner profile is that he had a skills coach when he was four. This is preposterous. To develop physical literacy in children (the ability for them to move their body safely in a defined way) is it recommend that the first sport the participate in is tumbling. Not gymnastics, but tumbling. This allows for kids to learn how to control their bodies. After that they can try different sports to see what ones they enjoy the most.
Some of the criticism of LTAD has to do with the fact games are moved to smaller surfaces, but even that has logic: kids get to play on a surface that is their size and they get to play more. If the ice surface is split into two or three playing surfaces, that means six teams playing at once instead of two. As kids get older and, their playing surface get bigger with them.
Another common criticism is about not showing the score. The reason for this is to put an emphasis on learning and not worrying about who wins or loses. Kids will keep score, but coaches should be allowing everyone to play, allowing mistakes, and making sure players are having fun. As they get older, the score is shown and standings are kept. Not keeping score is to ensure that everyone has the same chance to love the game and play more than anything else.
One important part about LTAD and this should be applied to all athletes, even elite ones, is that specializing too early is a bad idea. It might seem smart to spend money on your four year old working with a skills coach at the time, is not a smart idea long-term. It might seem worth it if your kid makes the NHL, but what benefits are there long-term. Your kid will not make the NHL because they had a skills coach at four. They make the NHL if they are talented, work hard, and get the right opportunities. Skills can be developed at their own pace and on their own.
How Mitch Marner trains now that he is in the NHL is no business of anyones except for the team who pays him and Marner himself: it is his job and he has to do it. What he did as a child prior to even playing in the OHL is interesting and shows why some families are unable to afford for their kids to continue playing hockey. LTAD, which was not around when Marner was young, is all about emphasizing play and development through play for all athletes. It allows them to develop a love of sport that can carry on for life. As athletes get older, the better ones can branch out, specialize, and dedicate more time to that one sport that they are great at instead of worrying about that when they are 10.
When you are young, sport should not be about who the best player is, but if kids are having fun and developing a passion for physical activity. As they get older, they can join a more competitive stream and train at a higher level. There is nothing about the earlier emphasis on fun and learning that will take away from the competitive later days if someone decides to pursue that route. The only difference is, there are no private coaches early on.