  Analytical calculations of extra-galactic cosmic ray spectra above ~10^17 eV
are often performed assuming continuous source distributions, giving rise to
spectra that depend little on the propagation mode, be it rectilinear or
diffusive. We perform trajectory simulations for proton primaries in the
probably more realistic case of discrete sources with a density of
~10^-5/Mpc^3. We find two considerable non-universal effects that depend on
source distributions and magnetic fields: First, the primary extra-galactic
cosmic ray flux can become strongly suppressed below a few 10^18 eV due to
partial confinement in magnetic fields surrounding sources. Second, the
secondary photon to primary cosmic ray flux ratio between ~3x10^18 eV and
~10^20 eV decreases with decreasing source density and increasing
magnetization. As a consequence, in acceleration scenarios for the origin of
highest energy cosmic rays the fraction of secondary photons may be difficult
to detect even for experiments such as Pierre Auger. The cosmogenic neutrino
flux does not significantly depend on source density and magnetization.
