Review Detail of LightningCatThief in Practicing Basic Sorcery for Billions of Times Made Me Invincible

This novel is barely in the reading to pass time zone. The problem is that the world building and the mechanics of the magic system aren't defined in a consistent way. Which leads to the MC being awesome, but not comparable to anything. If one can reach a rank with enough training, why does the difference between spells matter so much? Why is it important to condese magic power? The author simply tells us it is and we as the readers have to accept it. An example is the fact that the MC always practices only the basics of magic and so far only one element. Why? Why are the basics so important? I understand that the basics can strengthen the foundation and this is important, but even the most patient and wise humans on the planet know that advanced techniques are important in any field, that is why they were developed. It feels like the only reason the MC practices at all is to get the system rewards, which is what actually gives him strength. It is like he goes to work every day for money, he doesn't gain anything during practice, he just gets rewarded for doing so. MC is also way to passive and mostly a nonentity in this story. We could literally exchange him for any other student and nothing would change.