SureshKoya
Is there any specific reason for using separate properties? In that case, we need to write a when condition that would evaluate all the properties in OR condition to check if at least one of the days is selected.
We would strongly recommend using a repeating dynamic layout with a Page list as a source. We can source the page list from a data type or activity based on our convenience.
Now on click of submit, use OOTB functions like IsInPageList or CountInPageList to validate if at least one of the day is selected form the list.
Let us know if this design satisfies your need.