Hi! Since I am the one (vivka) who suggested the original code at a different forum, I can offer an improved version of it:
Sub Tbl_Add_Row()
'In the selected tbl, insert a row after each n-th row.

Dim LastRow As Integer, RemainderRows As Integer, CountBy As Integer
    Application.ScreenUpdating = False
    
    CountBy = InputBox("Enter the number to count rows by:", "ENTER A ROW AFTER EACH...")
    LastRow = selection.Tables(1).rows.count
    RemainderRows = LastRow \ CountBy
    
    If LastRow Mod CountBy = 0 Then
        LastRow = LastRow
    Else: LastRow = CountBy * RemainderRows
    End If
    For i = LastRow To 2 Step -CountBy
        selection.Tables(1).rows(i).Select
        With selection.Tables(1).rows(i)
            selection.InsertRowsBelow 1
        End With
    Next i
    Application.ScreenUpdating = True
End Sub