Be careful about making generalizations about this. The position of the
peak current depends on frequency and the ground characteristics. I
believe it's also a function of the height of the vertical. In some
cases there's no real peak at all, but an exponential-looking decay of
current from the base of the vertical outward. This, incidentally, was
experimentally measured and documented by Brown, Lewis, and Epstein in 1937.

Roy Lewallen, W7EL

Dan Richardson wrote:

Maybe the difference is the length of the radials. I used ½-wavelength
radials as the peak ground current is at 0.35-wavelength from the base
of the monopole - ¼-wavelength radials would be too short to reach
that area.

Danny