Novble, maybe we are missing each other's points here.
As a parent, I don't have your markbook. Because books aren't marked in the same way as they are at primary, I can't see from looking at DC's books how well they are doing. I am not in class, so don't know whether they contribute, are silent, or are disruptive. You may not feel you are telling me anything when you transmit information from your markbook or your in-class observations to me, but you are.
So for me, in the years that DC have had two parents' evenings, I have found both of these useful, particularly because they are well-timed to have different purposes (settling in / options or A-level choices / focus for revision) and because I don't know whether DC are good in geometry and poor at algebra. I find a teacher's interpretation of this 'they did OK relative to the class in algebra despite the relatively low raw mark. They all found the subject hard and we will be revisiting again before the exams - check the revision timetable too, because although I think they needn't come every week, I think they should come for algebra, circle theorems and graphs' much more informative than an automatically generated printout of the mark book would be (though of course with numerical reports I get a summarised version of your markbook anyway, and we get those before the parents' evening).
The two meetings are different a) because they are well-timed to have different purposes and b) because the children have obviously covered different topics in between. So 'They did excellently when we were doing drawing, but are finding painting much more challenging' in art, or 'Much more engaged since we started X book' in English, or 'We've come back to algebra and recent marks show they're much more secure' in Maths.
I would also say that the 3-4 hours of a parents' evening is surely much less hassle than full written reports, which we do get every few years - those years without 2 parents;' evenings, IIRC? I know that for primary, I would FAR prefer our two evenings per term of parents' evenings face to face in the first 2 terms of the year than the final written report that we do in the third term, as they're so much more efficient in terms of information transferred per unit of time spent!