Need help coding Lookup Statements

[ZooTV92]

Sample Worksheet.xlsxSample Worksheet.xlsxSample workbook attached.

I am currently using this code, thanks to the help of this board to check against scheduling the same employee in a shift. I have tried in vain to utilize this template to further code the rest of the workbook.

'Private Sub Worksheet_Change(ByVal Target As Range)

check for duplicate shifts (Friday)
    Dim myrange As Range
    Set myrange = Range("L8:L187")
    If Not Intersect(Target, myrange) Is Nothing Then
        Application.EnableEvents = False
        If WorksheetFunction.CountIf(myrange, Target) > 1 Then
            MsgBox "This employee has already been scheduled during the matinee shift.", vbExclamation + vbOKOnly, "Duplicate Shift"
            ActiveCell.Select
            Selection.ClearContents
            
        End If
        GoTo exit_sub
    End If

Set myrange = Range("AB8:AH187")
    If Not Intersect(Target, myrange) Is Nothing Then
        Application.EnableEvents = False
        If WorksheetFunction.CountIf(myrange, Target) > 1 Then
            MsgBox "This employee has already been scheduled during the evening shift.", vbExclamation + vbOKOnly, "Duplicate Shift"
            ActiveCell.Select
            Selection.ClearContents
        End If
        
    End If
exit_sub:
    Application.EnableEvents = True

End Sub

Explanations of what I am after included in the very basic attached workbook.

Any help is greatly appreciated.