Here, it is totally class and teacher specific, no set rules or pattern. I don't think DD had many mid-terms, one in AP world history before the break that I remember, but that's it. Our second marking period (of four) ends near the end of January; there seem to be exams in many classes just before the end of the marking period, but they are usually not midterms or cumulative, at least not in our experience.
Our state, NY, does hold regents exams mid-year, after the break here (but regents exams are final exams, not mid-terms, so I assume these are for kids who are taking make-up exams or are off the typical year-long sequence for some other reason- no personal experience here.)
