Can a professor rely on Blackboard flagging idle time spent on answering multiple choice questions to 'prove' academic dishonesty?

So for closed-book online exams, I tend to stare at the question for a while before I move on to the next one and nothing ever happened afterwards. I just take my time reading the question and answer it in my slow pace. They were on Canvas and Pearson. But for this class, the professor says Blackboard flags students that idle on a question for an exceptionally long time and are assumed to be 'looking up the answers'. What is considered an 'exceptionally long' time? 1 minute? 2? 3? I don't know. So my question is, can the professor accuse me of cheating if I genuinely took a while to answer several questions during the exam? Will it hold up in an academic dishonesty investigation? Or do they need other kinds of evidence?