You might want to account for the number of business days within a month or week in your model if your business is highly responsive to this. Luckily Causal has an easy solution!
You can create a daily model and use the helper variable dayOfWeek to determine if the day is a Saturday or Sunday. 0 = Sunday and 6 = Saturday. Causal also has many holidays built in as helper variables so you can use these as flags too.
Together you can create a formula like the below:
This labels any business day as 1 with 0 for the remainder.
Now you can create a linked monthly/weekly model which references this variable and Causal will sum all the days up for each respective month/week to calculate the business days per month/week as desired!