One of my students has a spreadsheet that they use for tracking employees
scheduled work days. Rows are the employees names, columns represent the day
of the week. The columns are repeating - Sunday through Saturday, over and
over to cover 3 months. Under the day of the week they enter a code that
signifies what shift was worked for that employee.

They want to know if there is a way to calculate how many times in that 3
month timeframe the employee worked each day of the week. So, how many
Sundays did Mary work in those three months? How many Mondays, etc.

Is this possible?