I am a completionist so I try to 100% everything. Not just the gallery, but also in terms of looking at all unseen text, so I pick the other choices as well to see what happens. It just feels like I haven't completed a game unless I look at everything (and it also feels more respectful to the creators to do so) so I feel compelled to do so no matter what.
But even so, there are many times when I'm not that interested in the story and don't really feel like playing, so I end up procrastinating and leaving something unfinished (even if I tell myself I'll eventually get back to it). So even though I am a completionist, my completion rate isn't actually that high... Still, I feel like a game isn't finished unless I 100% it, so even for past games where I have basically read the entire main story (but haven't looked at or collected everything), I consider them closer to indefinitely on-hold rather than completed.