With WS
    For i= 2  To .Cells(.Rows.Count, 1 ).End(xlUp).Row
        MsgBox .Cells(i, 1 )
    Next i
End With

WS.UsedRange

 Type    Required XlCellType. The cells to include.
...
xlCellTypeLastCell. The last cell in the used range 
...

Sub test1()

    [B5:B50] =  1      
    MsgBox Cells.SpecialCells(xlCellTypeLastCell).Row 'правда

    [ 30 : 50 ].Delete
    MsgBox Cells.SpecialCells(xlCellTypeLastCell).Row 'вранье

    x = UsedRange 'пересчитываем и... 
    MsgBox Cells.SpecialCells(xlCellTypeLastCell).Row 'правда
    
    [B1:B90].Interior.ColorIndex =  5 
    MsgBox Cells.SpecialCells(xlCellTypeLastCell).Row '...кому как...
    
End Sub

    [A1:C3] =  1 
    [F6:H12] =  2 
    [K7:N9] =  3 
    [A1:Q90].Interior.ColorIndex =  40 

Sub test1()
    Dim rng As Range
    
    [A1:C3] =  1 
    [F6:H12] =  2 
    [K7:N9] =  3 
    [A1:Q90].Interior.ColorIndex =  40 
    
    Set rng = Cells
    MsgBox Intersect( _
      rng.Find("*", rng( 1 ), xlValues, xlWhole, xlByRows, _
        xlPrevious).EntireRow, _
      rng.Find("*", rng( 1 ), xlValues, xlWhole, xlByColumns, _
        xlPrevious).EntireColumn).Address
End Sub

Sub test2()
    Dim rng As Range
    
    [A1:C3] =  1 
    [F6:H12] =  2 
    [K7:N9] =  3 
    [A1:Q90].Interior.ColorIndex =  40 
    
    Set rng = Cells
    MsgBox rng.Find("*", rng( 1 ), xlValues, xlWhole, xlByRows, xlPrevious).Address
End Sub

\'---------------------------------------------- \nFunction LastCell(ws As Worksheet) As Range \n  Dim LastRow&, LastCol% \n\n\n   \'From Rodney Powell, Microsoft MVP \n   \'"The sample procedure below is a variation on a \n   \'technique I learned from fellow Excel MVP, Bob Umlas." \n   \' \n   \'http://www.exceldeveloper.com/geeks012.shtml \n\n\n  On Error Resume Next \n  With ws \n  \' Find the last real row \n    LastRow& = .Cells.Find(What:="*", _ \n      SearchDirection:=xlPrevious, _ \n      SearchOrder:=xlByRows).Row \n  \' Find the last real column \n    LastCol% = .Cells.Find(What:="*", _ \n      SearchDirection:=xlPrevious, _ \n      SearchOrder:=xlByColumns).Column \n  End With \n\n\n\' Initialize a Range object variable \n\' for the last populated row. \n  Set LastCell = ws.Cells(LastRow&, LastCol%) \n\nEnd Function