We now have LOE (Line Orientated Evaluation) every year for our Summer sim. So we no longer have an OPC, just an LPC evey year. The LOE is based on OFDM collected for that year, and any training issues picked up in the sim or on line flights. It is no longer based on one or two major failures (i.e. double hydraulics), but a series of small failures/gotchas.
For example, a typical LOE may be on the lines of a one hour sector, starting at the gate. LMC with up coming slot. Possible change of runway on taxi out. Pack out prior to departure..........and so on throughout the day out.
The LOE generally will have one occurrence during each phase of flight.
It is very realistic, in as much as it feels like a normal line flight, just with a few failures etc.
The really good thing is that day 2 in the sim is used solely for training, which we could all do with!