Multi-walled carbon nanotube networks were confirmed to exhibit a linear decrease in resistivity with increasing temperature from 100 to above 400 K. The linearity was explained using a defect scattering model that involved Friedel oscillations (that is, electron- electron interactions). The applicability of this model, which was originally proposed for graphene, to carbon nanotubes was assessed based on a comparison of various experimental data. Increases in the slopes of the resistivity-temperature plots following the introduction of defects, as well as an effect of charge concentration on the slope were key predictions of this model. The results obtained from few-walled carbon nanotube networks are also shown. In the literature, linear resistivity-temperature plots were obtained from other graphene derivatives, indicating that the linearity originates from the hexagonal symmetry of these materials. The present work also indicated a relationship between the appearance of linearity and negative magnetoresistance above 100 K. Based on a mechanism incorporating scattering in association with Friedel oscillations and conventional electron conduction models, the universality of resistivity-temperature plots obtained from carbon nanotube networks is introduced.