Cecil Moore wrote:

is only 40% shortening. I think the lumped inductor
crossover point is probably pretty far below 4 MHz.
73, Cecil http://www.qsl.net/w5dxp

There isn't any "crossover point". That point has been made several
times by different people.

There is a gradual transition over a very wide frequency range, and a
rapidly increasing change as self-resonace is approached.