  Ultra-clean graphene sheets encapsulated between hexagonal boron nitride
crystals host two-dimensional electron systems in which low-temperature
transport is solely limited by the sample size. We revisit the theoretical
problem of carrying out microscopic calculations of non-local ballistic
transport in such micron-scale devices. By employing the Landauer-Buttiker
scattering theory, we propose a novel scaling approach to tight-binding
non-local transport in realistic graphene devices. We test our numerical method
against experimental data on transverse magnetic focusing (TMF), a textbook
example of non-local ballistic transport in the presence of a transverse
magnetic field. This comparison enables a clear physical interpretation of all
the observed features of the TMF signal, including its oscillating sign.
