Doped organic semiconductors are critical to emerging device applications, including thermoelectrics, bioelectronics, and neuromorphic computing devices. It is commonly assumed that low conductivities in these materials result primarily from charge trapping by the Coulomb potentials of the dopant counter-ions. Here, we present a combined experimental and theoretical study based on systematically varying the shape and size of the dopant counterions to investigate the key factors that govern charge transport in a regime of high doping concentration. We find that conductivities are not limited by Coulombic trapping in this regime, but instead by paracrystalline disorder as well as Coulombic interactions between the carriers. In the talk we will provide a general overview over the factors that limit charge transport in these highly doped conjugated polymers.