I also notice that 19-25 change directors a staff members a great deal. That can slow your progression down. A different directors with new ideas & direction that not on board with the current staff. Now you hire a new staff, you drop from 16 to 22, now it takes 2-3 yrs just to get back to 16-18 placement. This becomes a cycle
for about 8-9 yrs with some corps bouncing from 17-23 depending on the 2-3 new hot the trot failed directors within this time period or no consistence staff. The top tier corps aren't having stability problems like the lower tier corps are having which keeps some corps fighting it out with some OC corps. The bottom line is, new great idea corps director every so many years and staff = 19-23 placement.