Total number of fragments present in the entire disk as a function of time in the ξ = 5% model (top panel), ξ = 50% model (middle panel), and ξ = 95% model (bottom panel). The vertical dashed lines indicate the onset of the Class II phase of disk evolution. Pink zones correspond to time periods in the Class II phase when fragments exist in the disk, and yellow zones show the time periods without any fragments in the disk. The red lines show , the mean minimum Toomre parameter in the disk.