The beast was already done by another company using their paint protection film. Unfortunately, the customer wasn't very happy with the way the bumper was done (had bubbles and creases in a few places) so they decided to get it redone and done properly.
There is more chance of the film lifting if it goes deeper as with heat etc the film will try to pull back. By trimming it on a flat surface it wont lift as easy and can therefore bond properly during the drying time.