This topic is the source of many discussions and fantasies. My view is the following:

- When IROPS are limited, and the situation is managed, the gate agents try to apply the op-up rules. On recent EU flights with overbooked coach sections, I got upgraded while my booking class was the highest (Y). Rules applied. But, as stated above by MSPeconomist, even in those cases, the gate agent may need a particular seat for special needs and a non status passenger with a low booking class could be upgraded to avoid a reshuffle of seats. Also there are sometimes last minute changes (among others passengers who have been predicted to not show up who eventually show up) that lead the gate agents to make last minute op-up to any passenger that has not yet boarded.

- When IROPS are major, such as the last that I experienced during the April strike in Germany, the check-in personel and gate agents are legitmately overwhelmed and focus their attention at trying to get as many passengers possible to fly. As a status passenger, the check-in agents made sure that I had a seat on a plane, but I do not believe that they had the capacity to apply the op-up rules in such a chaotic situation. Hence, to my view, any passenger has a chance in those cases.

Accordingly, there is little that can be done to maximize chances without deploying a lot of efforts (get status, look for overbooked flights and chaotic situations, buy higher booking classes) which are probably not worth the increase in chances.