I use drone comb in early spring to trap and remove varroa mites. This slows the mites growth rate so that often only one treatment is necessary in late summer. Drone brood removal is only effective early spring in this area, drone production is usually ending due to drought by late June or early July. Not so this year, we have drones galore due to the wet summer we are having.
The idea that removing drone brood selects for worker preference mites is incorrect, leaving mites that are reproducing in worker brood (that are by far the largest percent) would be more apt to select for worker preference than would removing drone brood. Researchers tried to select for worker preference mites when varroa first became a problem, and they were unable to do so.
Miss removing a drone frame and allowing the drones to emerge really messes up a varroa management program, as I learned by experience this year. I found one colony which I failed to remove the 2 drone frames from, the alcohol wash count was 10 times greater than the other colonies in my home yard.