Leveraging the high performance of the newly developed hSPEPS for dipolar-based C- C transfers, we assessed whether the extended mixing time and reliance on J-coupling transfers in TOCSY could explain some missing C assignments. We recorded double sensitivity-enhanced 3D hCXcaNH spectra employing hSPEPS and zTOCSY. However, no additional C peaks, unassigned in the 4D TOCSY spectra, were identified in the 3D hSPEPS spectrum. A comparative analysis of the intensities of isolated C-N-H peaks in the 3D spectra indicated that zTOCSY generally outperformed hSPEPS (see SI Fig. ). This suggests that the TOCSY-based approach is suitable for membrane proteins, and the missing side-chain assignments in GlpG are likely attributed to internal dynamics and lipid-protein interactions interfering with both dipolar and J-coupling-based magnetization transfers.