Billable Hours Attempt - WeekdaySub counting Saturday as weekday

Here is another formula to try.

// input your own business hours and datetime fields which are your start and end. 

var timeofday DayStartTime = ToTimeOfDay("6:00 am");
var timeofday DayEndTime = ToTimeOfDay("6:00 pm");
var datetime StartClock = [Date Created];
var datetime EndClock = [Closed Date];

var DateTime StartDateTime = Max($StartClock, ToTimestamp(ToDate($StartClock), $DayStartTime));
 
var DateTime EndDateTimeTesting = If(IsNull($EndClock), Now() ,$EndClock);

var DateTime EndDateTime = Min($EndDateTimeTesting, ToTimestamp(ToDate($EndDateTimeTesting), $DayEndTime));

var Number WeekDayDays = WeekdaySub(ToDate($EndDateTime), ToDate($StartDateTime)) + 1; //(we count each day as a full workday) 

var number HoursBeforeStartEndAdjustment  = $WeekDayDays * ToHours($DayEndTime - $DayStartTime);

var datetime StartDateTimeBounded = 
  If(ToTimeOfDay($StartDateTime) < $DayStartTime, ToTimestamp(ToDate($StartDateTime), $DayStartTime), $StartDateTime);

var datetime EndDateTimeBounded = 
If(ToTimeOfDay($EndDateTime) > $DayEndTime, ToTimestamp(ToDate($EndDateTime), $DayEndTime), $EndDateTime);

Max(0,
Round($HoursBeforeStartEndAdjustment 
- Max(0,ToHours(ToTimeOfDay($StartDateTimeBounded) - $DayStartTime)) 
- Max(0,ToHours($DayEndTime - ToTimeOfDay($EndDateTimeBounded))),0.1))