All kids need repetition to learn - the level of repetition is dependent on the children. There is a 0% part of the population that picks up math or language without repeats. Also, work ethic and grinding is part of every humans life - there are 0 jobs without an aspect of grind and work. Much like learning, research and discovery requires grit which can be learned.
If you want to argue some children learn faster and can level up faster thats obviously a true statement.
Your "brighter kids" probably did their reps already, when you weren't watching. My 4 year old likes to quiz me on addition and subtraction at the dinner table -- two years from now, in some school, it'll look like he 'just gets it', which he will, but only because he already did his reps.
Couldn't agree more with you. I have kids of the same ilk. There certainly a differential in children's natural aptitude but they all do reps either publicly or privately - many people just don't realize it e.g. OP.
If you want to argue some children learn faster and can level up faster thats obviously a true statement.