Worksheet Change Target Ranges

I have the following worksheet change code. My question to the forum is what is the best practice for identifying target range? The below code runs on a worksheet that has 12K lines and growing. To manage this code most efficiently as it grows and changes, is it best to use named ranges for the target range or simply identifying the ranges (ie rngcheck)? I am open to changing code if necessary. It may be that there is no significant advantage either way. I am still learning VBA and would appreciate any advice. Thanks in advance.

Private Sub Worksheet_Change(ByVal Target As Range)

Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
Application.EnableEvents = False

   Dim Answer As Long
   Dim Lrow1 As Long
   Dim rngCheck As Range
   Dim CheckCell As Range
   Dim Lrow As Long
   Dim WS1 As Worksheet
   Dim WS2 As Worksheet
   Set WS1 = Sheets("TEST")
   Set WS2 = Sheets("TEST2")

    Set rngCheck = Intersect(Target, Range("C3:C5, C7:C1234, C1236:C12000"))

    If Not rngCheck Is Nothing Then
        For Each CheckCell In rngCheck.Cells
            If CheckCell.Value > 0 Then

              With WS1.UsedRange
                    Lrow = .Cells(.Rows.Count, "D").End(xlUp).Row + 1
                    WS2.Cells(CheckCell.Row, "C").Copy
                    WS1.Cells(Lrow, "D").PasteSpecial xlPasteValues
                    WS2.Cells(CheckCell.Row, "B").Copy
                    WS1.Cells(Lrow, "K").PasteSpecial xlPasteValues
                    WS2.Cells(CheckCell.Row, "E").Copy
                    WS1.Cells(Lrow, "J").PasteSpecial xlPasteValues
                    WS2.Cells(CheckCell.Row, "D").Copy
                    WS1.Cells(Lrow, "E").PasteSpecial xlPasteValues
                End With
            End If
        Next CheckCell
    End If

    

 Set rng1Check = Intersect(Target, Range("C2,C6"))
 If Not rng1Check Is Nothing Then
        For Each Check1Cell In rng1Check.Cells
           If rng1Check.Value > 0 Then
        
 Answer = MsgBox("Add Assembly Kit Yes or No.", vbYesNo)
 Lrow1 = WS1.Cells(WS1.Rows.Count, "D").End(xlUp).Row + 1
 Select Case Answer
  Case vbYes
                    WS2.Cells(Check1Cell.Row, "C").Copy
                    WS1.Cells(Lrow1, "D").PasteSpecial xlPasteValues
                    WS2.Cells(Check1Cell.Row, "B").Copy
                    WS1.Cells(Lrow1, "K").Value = Target.Offset(0, -1).Value & " " & "w/Assembly Kit"
                    WS2.Cells(Check1Cell.Row, "D").Copy
                    WS1.Cells(Lrow1, "E").PasteSpecial xlPasteValues
                    WS1.Cells(Lrow1, "J").Value = Target.Offset(0, 2).Value + 10
           
 Case vbNo
 
                  
                    WS2.Cells(Check1Cell.Row, "C").Copy
                    WS1.Cells(Lrow1, "D").PasteSpecial xlPasteValues
                    WS2.Cells(Check1Cell.Row, "B").Copy
                    WS1.Cells(Lrow1, "K").PasteSpecial xlPasteValues
                    WS2.Cells(Check1Cell.Row, "E").Copy
                    WS1.Cells(Lrow1, "J").PasteSpecial xlPasteValues
                    WS2.Cells(Check1Cell.Row, "D").Copy
                    WS1.Cells(Lrow1, "E").PasteSpecial xlPasteValues
       
 End Select

       End If
    Next Check1Cell
 End If


Application.EnableEvents = True
Application.ScreenUpdating = True
Application.Calculation = xlCalculationAutomatic
End Sub

If you use dynamic named ranges, especially for the last one, then the code would be similar to:

 If Not Intersect(Target, Union(Range("test1"), Range("test2"), Range("test3"))) Is Nothing Then

and at least that part of the code would not have to be edited as the data grows.