Lanyard Calendar - Highlight rostered shifts

Hi All,
I need assistance as i am confused to make this more user friendly (or mainly reduce the time i need to spend building calendars for each year)..

I'd like help please on creating something similar to the attached with 2 versions of rosters (4on 4off and 4on 5off).
I want the calendar to auto create based off the year the user chooses and then highlight the days based off the roster they choose.

You will see the 4/4 roster is 4 teams doing DDNNOOOO (Alpha, Bravo, Charlie, Delta) - This then repeats every 8 weeks
You will see the 4/5 roster is 9 teams doing DDNNOOOOO (Alpha1 & 2, Bravo1 & 2, Charlie1 & 2, Delta1 & 2, Echo) - This then repeats every 9 weeks

I'd like to be able to enter dates to highlight of public holidays (but not essentially needed as sometimes they do changes or we get additional ones).

If you can save me heaps of time each year having to expand this calendar and making sure i don't stuff up the manual highlighting i do that would be greatly appreciated.

Thank you in advance.