How Often Do you Get Skunked on FCFS Camp Spots?

Also doing the 9-5 situation with weekends off, so reservations are necessary most of the time. Most USFS campgrounds in this area need reservations, and there are few FC/FS sites in those CGs. There are some FC/FS campgrounds in this area of northern Colorado, all sites are non-reservable. Going to try my hand at boondocking in the Snowy Range of Wyoming in August, with a fall back of using one of the USFS CGs up there (that are all FC/FS CGs).