The equivalent circuit is WRONG. I do not know how long that ignorance from 19th century will continue replicating. The capacitance grows with the coil length, and in the circuit it decreases. The capacitance is a multi-dimentional solution of Maxwell equations and can not be approximated simply by wire layers. At RF it may be approximated in cylindrical coordinates through the wave equation with periodic boundary conditions. But the good solution requires FEM simulation.