Formation efficiency of star clusters (thick solid line) and of sinks that remain starless (dashed thin line) among our suite of clouds as a function of the initial freefall timescale of the cloud. From left to right, we show clouds in which we modify the growth of star clusters, their feedback mechanisms, as well as the initial gas surface density of the cloud. The black solid line present in all panels corresponds to our fiducial cloud. Through most of its evolution, the fiducial cloud forms mass in clusters more quickly than the cloud evolved with the standard star formation prescription, but the formation stops at t ≃ 12 Myr.