Dim sh As Worksheet, lr As Double, arr, arr2, i As Double, j As Double, a As Double
Set sh = Sheets("Sheet1")
With sh
lr = .Range("A" & .Rows.Count).End(xlUp).Row
arr = .Range("A1:A" & lr)
ReDim arr2(1 To lr * 12)
.Columns("B").ClearContents
For i = 1 To lr
For j = 1 To 12
arr2(j + a) = arr(i, 1)
Next
a = a + 12
Next
.Range("B1").Resize(UBound(arr2)) = Application.Transpose(arr2)
End With