If a nock wears out or gets cracked, it is easier to replace if it is press fit. OTOH, press fit nocks tend to move out of place easier, so I have to glance down and see if I need to give it a twist to adjust it. If a press fit nock breaks off at the insert, it is kind of a mess. Most fletching tools have limited options for indexing, so it is convenient to be able to twist the nock into that perfect place, if you are picky about that kind of thing. I've heard that some people who prefer glue-on nocks glue them on after fletching the arrow, as the glue on nocks evidently have enough friction to hold them in place while being fletched. So each has its pros and cons.