Yes it is possible. I have not done a full engineering or performance study but I would assume that process uses some system resources. Does it eat them up? I don't think so. You will have to try it for yourself:
Code:
Sub Reminder()
Application.OnTime Now + TimeValue("00:30:00"), "ReminderMsg"
lbl_Exit:
Exit Sub
End Sub
Sub ReminderMsg()
If MsgBox("Wake up. Do you want to continue 30 minutes wake up calls?", vbYesNo, "Stop") = vbYes Then
Reminder
End If
lbl_Exit:
Exit Sub
End Sub