As mentioned, I think Nodoka IS a good character, in the sense that her motivations aren't just one-dimensional as they may appear. But she's not a good person, though I don't think she's evil for the sake of it. I mean, either she was already broken before, or the cycles broke her, but she came off to me as someone with an "end justifies the means" mindset, who cherishes Futaba, who legitimately didn't see anything wrong with publishing the book about them because it couldn't be conclusively proven it was about them, who will torture Yumi in a bid to see what makes her tick (and when Sensei is there, to test him too), who will try ANYTHING to see how the loop they found themselves in works, including getting all kinds of reactions from her classmates to see exactly what's the limits they are allowed to reach.
I do think, however, that she HAS been hard reset before, but it's not a certainty, mostly because of the bit that she tortured Yumi in one of the other timelines, which, if you take her being practical to its extreme, would serve no logical purpose unless she hasn't done so before.