Couple things.

First, yes, if the Boss is changed or removed, POI may change.

Also, practice should involve known distance shooting to the extreme range of shots you will fire. We spend little time on the bench, and use it for what I call rough-zeroing the rifle only, then get on the ground and shoot from sitting, mostly, and kneeling and some close range standing. Such a routine also teaches the limitations of the shooter. This last bit is important, because all of us have different skills and comfort levels with a rifle. Knowing what YOUR limit is, is far more important than knowing what your RIFLE's limit is. Most rifles shoot better than we do...

Taping the trajectory on the stock is not necessary for big game with many high velocity rifles, but it sure does help morale {I do it on some slower round calibers and varmint guns}, especially if you have a range finder and have shot your rifle enough to set up a table that includes 50-meter increments all the way out to say, 450 meters or so. Past 300 every 50 meter change in distance can have a very pronounced impact on POI. That's why some of us prefer to use 300 as a max range for big game shooting. Sighted right and depending on bullet/load, even with a .375 H&H Magnum, no holding over the animal is required even at 300 if the animal is a big deer or elk or moose.