Ratio between the initial and final values of the inner binary pericentre with respect to the outer binary initial separation, normalised to the inner BHB initial semi-major axis, a_i = 20 AU. From left to right and from top to bottom panels: SET1 (e_i = 0, Δϖ_i = 0 − 2π, i_i = 0°), SET2 (e_i = 0, Δϖ_i = 0, i_i = 0 − 10°), SET3 (e_i = 0 − 1, Δϖ_i = 0, i_i = 0 − 10°), and SET4 (e_i = 0 − 1, Δϖ_i = 0, i_i = 0 − 180°), respectively; see Table 2. The colours represent the ratio between the final and initial value of the GW timescale for the inner binary. Bottom panels: same as in top four panels, but here we show the inner binary final eccentricity vs. the semi-major axis ratio.