Interesting thing I noticed: Because Rosh Chodesh is always the day after the 29th of the month (either the 30th or the 1st) and the 29th is the same day of the week as the first so the days of Rosh Chodesh go in order so if Rosh HaShana is a Monday, then R”Ch Cheshvan would be Tuesday and Wednesday, R”Ch Kislev would be Thursday and possibly Friday, etc.
This can make it easier to figure out what day of the week a Yom Tov will be on months in advance assuming you know what day the most recent R”Ch was and how many days each month’s R”Ch has