I have NEVER gotten an upgrade during OLCI. If no upgrade at the 5 day window, then the probability of upgrade gets very low. I have had 3 or 4 at the gate, but usually not. Overall upgrade percentage is around 50% (perception, not measured). Since I buy low cost advance fare tickets, I am pleased when I get upgraded, and not unhappy when I don't. After all, I could always pay more and get up front more often if it was important.