The authors have examined the room-temperature basal-plane resistivity for a wide variety of acceptor (Br2, HNO3, AlCl3, GaCl3, FeCl3, SbCl5, NO2X (X=BF4, PF6, SbF6)) and donor (Li, K, Rb, Cs) graphite intercalation compounds. Plotted as a function of inverse stage, the resistivity first undergoes a rapid decrease until a dilute intercalation compound is formed; beyond this point to a saturated product forming, the conductivity change is significantly reduced. The contributing factors are discussed: the intercalation-produced dilation and defects, charge transfer between intercalant and host, its c-axis distribution and the mobility of the carriers involved.