Your workdays seem to be special :-)
it says under BUSINESS CONFIGURATION VARIABLES
… WorkWeekBeg must come before WorkWeekEnd numerically so there is no way to handle a work week of Sunday to Thursday using these variables.
To handle a work week of Sunday to Thursday, just set WorkWeekBeg=1 and WorkWeekEnd=7 and defined a holiday that occurs every Friday and Saturday.
… can be done using recurrences. Refer to the Date::Manip::Recur documentation for details.