It is expensive shooting these premium slugs and that's good advise. What I do is shoot my first two shots at 50 yrds on a 1 inch grided target then make a adjustment according to the scope turret adjustments ( 1/4" at 100yards will be 1/8" at 50 yards) then move back to 100 and fire two more.
If your shooting from a solid rest it should only take a couple of more shots to get whatever zero one should desire. Nothing substitutes practice , plan to shoot a couple of five round boxes a year, make ethical shots, everybody is watching us.gun)