  Explaining variability observed in the accretion flows of black hole X-ray
binary systems remains challenging, especially concerning timescales less than,
or comparable to, the viscous timescale but much larger than the inner orbital
period despite decades of research identifying numerous relevant physical
mechanisms. We take a simplified but broad approach to study several mechanisms
likely relevant to patterns of variability observed in the persistently
high-soft Roche-lobe overflow system LMC X-3. Based on simple estimates and
upper bounds, we find that physics beyond varying disk/corona bifurcation at
the disk edge, Compton-heated winds, modulation of total supply rate via
irradiation of the companion, and the likely extent of the partial hydrogen
ionization instability is needed to explain the degree, and especially the
pattern, of variability in LMC X-3 largely due to viscous dampening. We then
show how evaporation--condensation may resolve or compound the problem given
the uncertainties associated with this complex mechanism and our current
implementation. We briefly mention our plans to resolve the question, refine
and extend our model, and alternatives we have not yet explored.
