Creating a self adjusting work roster

Hi,

I am trying to create a self adjusting work roster. Ideally I would want everyone to work 4 days on and two days off. The only problem being accounting for when people get tasked out on different missions. Right now its all manual input and it makes it a very long and tedious process that has to be scrubbed time and time again to ensure no errors are done. Overall I would need 16 workers each day at a min. I don't really care how many are working as long as I have 16 each day. Thank you in advance I been melting my brain and have watched countless amount of videos trying to solve this. I will upload a example of my workbook.

Thank you