Agreed - some hens will amass a huge clutch before they start setting (and then there is the issue of "donated eggs" during incubation) while others will just go straight to brooding on an empty nest.
ETA - this is where flock management comes into play and if/when a hen sets to brooding *you* can assess how many eggs you feel she can comfortably and successfully cover as well as how many chicks you want/need and pick the number that fits in both categories and add or remove eggs accordingly on day 1, marking all eggs you want set and then checking the nest (if accessible to other hens) to remove any unmarked eggs