Because you have not defined blanks
You don't even need it if you want to do it just for A1 to A10
Use this:

Sub Macro()
For Each cell In Range("A1:A10")
Select Case cell.Value
Case "W"
cell.Offset(0, 1).Interior.ColorIndex = 1
Case "Q"
cell.Offset(0, 1).Interior.ColorIndex = 7
Case Else
cell.Offset(0, 1).Interior.ColorIndex = 9
End Select
Next
End Sub


"AlanW" wrote:

Could anyone please tell why the funnel is kept running without stopping even
after the expected task is completed.

Sub Macro()
Do Until blanks
For Each cell In Range("A1:A10")
Select Case cell.Value
Case "W"
cell.Offset(0, 1).Interior.ColorIndex = 1
Case "Q"
cell.Offset(0, 1).Interior.ColorIndex = 7
Case Else
cell.Offset(0, 1).Interior.ColorIndex = 9
End Select
Next
Loop
End Sub

Thank you