For myself, I am not concerned at all wether or not maximum black is created on the film edge being exposed. I would very much reccomend that you print for no more blackness than is neccessary to produce the print that you find pleasing. In my opinion worrying about maximum black is a very good way to end up with shadow detail not being visible. If you find that the unexposed film ege always is less than maximum it may well mean that you are underexposing your negatives. Lower your meter setting by 1/3 and if inadequate by 1/2 stop and see if you find that a fair percentage of your prints that show an unexposed film edge are now maximum black.