  Low-scale leptogenesis is most efficient in the limit of an extreme mass
degeneracy of right-handed neutrino flavours. Two variants of this situation
are of particular interest: large neutrino Yukawa couplings, which boost the
prospects of experimental scrutiny, and small ones, which may lead to large
lepton asymmetries surviving down to T < 5 GeV. We study benchmarks of these
cases within a "complete" framework which tracks both helicity states of
right-handed neutrinos as well as their kinetic non-equilibrium, and includes a
number of effects not accounted for previously. For two right-handed flavours
with GeV-scale masses, Yukawa couplings up to $|h| \sim 0.7 \times 10^{-5}$ are
found to be viable for baryogenesis, with $\Delta M/M \sim 10^{-8}$ as the
optimal degeneracy. Late-time lepton asymmetries are most favourably produced
with $\Delta M/M \sim 10^{-11}$. We show that the system reaches a stationary
state at T < 15 GeV, in which lepton asymmetries can be more than $10^3$ times
larger than the baryon asymmetry, reach flavour equilibrium, and balance
against helicity asymmetries.
