A long‐standing question surrounding rifted margins concerns how the observed fault‐restored extension in the upper crust is usually less than that calculated from subsidence models or from crustal thickness estimates, the so‐called “extension discrepancy.” Here we revisit this issue drawing on recently completed numerical results. We extract thinning profiles from four end‐member geodynamic model rifts with varying width and asymmetry and propose tectonic models that best explain those results. We then relate the spatial and temporal evolution of upper to lower crustal thinning, or crustal depth‐dependent thinning (DDT), and crustal thinning to mantle thinning, or lithospheric DDT, which are difficult to achieve in natural systems due to the lack of observations that constrain thinning at different stages between prerift extension and lithospheric breakup. Our results support the hypothesis that crustal DDT cannot be the main cause of the extension discrepancy, which may be overestimated because of the difficulty in recognizing distributed deformation, and polyphase and detachment faulting in seismic data. More importantly, the results support that lithospheric DDT is likely to dominate at specific stages of rift evolution because crustal and mantle thinning distributions are not always spatially coincident and at times are not even balanced by an equal magnitude of thinning in two dimensions. Moreover, either pure or simple shear models can apply at various points of time and space depending on the type of rift. Both DDT and pure/simple shear variations across space and time can result in observed complex fault geometries, uplift/subsidence, and thermal histories. Plain Language Summary The areas of the Earth where continental crust gives way to oceanic crust, the continental margins, are one of the most defining qualities of the tectonic plates. As continents extended ‐ as North America is doing in the US Basin and Range today ‐ and then rifted, sedimentary basins developed that hold enormous hydrocarbon resources. In some places the underlying mantle of the Earth approached the surface, and in others volcanoes erupted, and thus rifting plays an enormous role global geochemical cycles, such as control atmospheric CO2 over geologic time. Similarly, these margins preserve the record of sealevel change and climactic changes. Scientists mostly rely on seismic reflection data to understand this process of continental rifting, because most rifts are underwater and sediment. Thus, computational modeling has become a powerful tool with which to understand this process. Here, we use such computational tools to produce an analytical visualization commonly used to interpret seismic data. The result rules out many models for continental rifting, and rules in others, and points the way to research questions bearing on the Earth's crust and mantle. Key Points We show thinning profiles for modeled extensional margins Extension discrepancy is overestimated, and depth‐dependent thinning varies over space and time Crustal depth‐dependent thinning cannot solve the extension discrepancy, though detachment shear zones are required to accommodate thinning