The amount of time the binary spends at various orbital periods during its evolution towards merger. The three panels show different mass ratios, and in each panel the three sets of curves show different total masses as marked. For each mass, different line styles correspond to different types of migration, GW inspiral (green), saturated and unsaturated Type 1.5 (magenta dashed and solid), and Type II (black dotted). The evolutionary tracks are highlighted with a thick yellow line. Big black dots mark gap decoupling; for much smaller periods, the tidal torques may not generate EM variability.