We assess the fault impact on the stress field in northern Switzerland using 3D geomechanical models, calibrated with stress data. We see that faults affect the stresses only locally, with negligible impact beyond 1 km, suggesting that faults may not be necessary in reservoir-scale models predicting stresses of undisturbed rock volumes, such as for a geological repository. Omitting them can substantially reduce model set-up time and computational cost without compromising prediction reliability.