After giving all known contributions to coupling losses in superconducting flat structures with twisted filaments, we argue that in some structures the contribution, caused by the induced currents between filaments or striations on the same side of a flat cable or tape, generally cannot be neglected in calculating the total coupling losses. This contribution was not considered in previous calculations. As was demonstrated recently, this type of contribution can be decisive in determining the coupling losses for flat cables with well-conducting edge layers. We show that an analogous contribution should determine the coupling losses for flat cables with a central insulating layer and also for coated conductors with stripes or striations. In addition, it can restrict the maximum allowable twist pitch of superconductors with reliable loss generation and electromagnetic stability.