The lungs and guts are the starting point of the force for the entire cultivation technique, while the throat's Dantian acts as the endpoint for amplifying power.
If one possesses dual Dantians, naturally, the problem is easily solved.
However, with a single Dantian, it leads to the necessity of finding additional cultivation techniques to enhance the lungs and guts, to compensate for the weaknesses in the technique's power.
Among them, dietary and medicinal supplements, and various lung and gut cultivation exercises, whether in terms of time or materials, all represent significant consumption.
On the contrary, the techniques in the second bookcase generally do not have such obvious shortcomings or defects.
Even if slightly more conservative and mild in power, they allow the cultivator to steadily improve, rather than taking a risky path and leaving significant flaws that exhaust one's spirit trying to compensate with external forces.
