I used to help accomplish the annual tech. refreshers and we based the delivery on technical problems that had occured over the previous year.......
eg, if the fleet had an assymetric flap problem, we'd spend a bit of time reviewing the system. Also, if other operators had experienced an interesting technical problem we'd look at that in some detail.
Although it looked a bit like bolting the door after the horse had gone, we were able to work from a factual base on what, why and when it happened and most importantly, advice and suggestions (over and above the approved procedures) if it, or something similar, happened in the future.
Although inevitably most crew looked upon the Tech Refresher as an interruption to their days off, most said they'd found it interesting, useful and enjoyable at the end of the day(s).