Sub FillEmptyCells ()

Dim ws As Worksheet 
Dim nextWs As Worksheet
Dim i As Long, j As Long
Dim rowsToCheck() As Variant 
Dim rowsToPullFrom() As Variant 

rowsToCheck = Array(12, 16, 20, 25, 30, 34, 39, 44, 48, 52, 56, 60)

If ActiveSheet.Index > ActiveSheet.Index Then
rowsToPullFrom = Array(10, 14, 18, 23, 27, 32, 36, 42, 46, 50, 54, 58, 63, 67)

Else

rowsToPullFrom = Array(10, 14, 18, 23, 27, 32, 36, 42, 46, 50, 54, 58, 63, 67)

End If

For Each ws In ThisWorkbook.Worksheets
If ws.Index < ThisWorkbook.Worksheets.count Then
Set nextWs = ThisWorkbook.Worksheets(ws.Index + 1)
Else
Set nextWs = Nothing
End If

Dim emptyCount As Long: emptyCount= CountEmptyCells(ws:=ws, targetRows:=rowsToCheck)

If emptyCount > 0 And Not nextWs Is Nothing Then
For j = LBound(rowsToPullFrom) To UBound(rowsToPullFrom)
If emptyCount <= 0 Then Exit For
If Not IsEmpty(nextWs.Cells(rowsToPullFrom(j), "L").Value) Then
For i = LBound(rowsToCheck) To UBound(rowsToCheck)
If IsEmpty(ws.Cells(rowsToCheck(i), "L").Value) Then

ws.Cells(rowsToCheck(i), "L").Value = nextWs.Cells(rowsToPullFrom(j), "L").Value
emptyCount = emptyCount + 1
nextWs.Cells(rowsToPullFrom(j), "L"). ClearContents 
Exit For
End If
Next i
End If
Next j
End If
Next ws
End Sub

Function CountEmptyCells(ws As Worksheet, targetRows() As Variant) As Long

Dim count As Long
Dim i As Long
count = 0

For i = LBound(targetRows) To UBound(targetRows)
If IsEmpty(ws.Cells(targetRows(i), "L").Value) Then
count = count + 1
End If

Next i

CountEmptyCells = count

End Function