Convergent CV evolution when the CARB model for magnetic braking is adopted for different initial post-CE binaries. The colour represents the log-scaled surface hydrogen abundance of the donor. Systems can be considered as AM CVn binaries if they reach shades of blue. Related objects, that is, CVs, transitional CVs, and He CVs are indicated by shades of other colours. While the assumed initial post-CE orbital periods cover values from 1.98 to 3.00 d, we fixed the initial post-CE white dwarf mass to 0.8 M_⊙ and the initial post-CE companion mass to 1.1 M_⊙. The evolution of the surface hydrogen abundance is strongly dependent on the mass of the helium core at the onset of mass transfer: the more massive the helium core, the lower the surface hydrogen abundance at a given orbital period during post-orbital-period-minimum evolution. CVs with donors having initially less massive helium cores bounce at longer orbital periods, leading to more massive and larger donors during AM CVn binary evolution. Along with the evolutionary tracks we included the following observed systems: CVs harbouring nuclear evolved donors (red diamonds), transitional CVs (cyan circles), He CVs (magenta squares), and AM CVn binaries (yellow stars), as described in Sect. 2.4. Except for AM CVn itself, the one with largest donor mass among AM CVn binaries, the characteristics of all AM CVn binaries can be explained by the CV channel, which means that the lack of hydrogen lines in the optical spectra of AM CVn binaries cannot be easily used as an argument against the CV formation channel. See Sect. 4.1 for more details.