Normalised torques vs the K-parameter range proposed in this study for the mass ratio 5 × 10⁻⁴ < q < 2 × 10⁻² a) with fixed α = 10⁻⁴ and Σ₀ = 10⁻⁴, varying h₀ or s; b) with fixed α = 10⁻⁴, h₀ = 0.05, and s = 0.5, varying Σ₀; c) by changing h₀, s and Σ₀ to simulate realistic conditions along the disc; d) with fixed Σ₀ = 10⁻⁴, h₀ = 0.05, and s = 0.5, varying α. Same colour palette as in Figure 1.