The problem with rescue skills are they are rarely practiced to a sufficient level to be effective. Even instructors rarely practice the drills apart from when they teach a rescue course. So we have a situation where people are learning from people who are not practiced.
Generally an instructor will operate a 1 in 3 continual education rate. So you need 9 open water students, to create 3 adventure/advanced divers, to create 1 rescue diver candidate. So the vast majority of time instructors are not teaching rescue diving regularly. The problem goes further, teach an inexperienced diver rescue skills and they are still in a situation of having to look after themselves so they don't become the next victim. When I was teaching on a daily basis I was so comfortable in the water that I felt I could completely handle myself without much conscious thought allowing me to concentrate on my students. If I am honest I would say this was around the 500-700 dives completed mark. Many divers and instructors rarely get to complete this number of dives. To be fair others may be better divers quicker than I was, but I like to think I can hold my own (I am a PADI Master Instructor and BSAC Advanced Instructor).
Let's start at the top. Should instructors complete a rescue update on an annual basis? Maybe not that practical. When I was the chief instructor of our dive school we ran a rescue scenario for staff every 6 months. We always found areas we could improve on or techniques that were not as good as they could be. After all we are always learning, so at least regular practice kept us current. As experienced instructors our rescue scenarios were effective if not always perfect.
However when we ran a rescue weekend, not a course but a practice weekend, we learnt a few valuable lessons. Day one started in a surprise scenario flung onto the participants whilst I was pretending to brief them on the day's timetable a situation developed... Rescue divers rushed into the scenario without much planning or thought (read strategy). The rush involved divers forgetting their weight belts in the rush to get started. A basic error few novice divers would make, but task loading a diver quickly, add stress (shouting) and simple mistakes are made. At least with experienced divers or instructors these basic errors are unlikely. A diver with less than 100 dives is still very much a novice.
An important element of the rescue course is self help and I think this is the greatest skill participants should take away from the course. So if rescue divers can't rescue, who should? When you pass your driving test they don't teach you how to perform rescue skills like how to cut someone free of a car or how to perform paramedic skills. You are taught to call the professionals, the emergency services, who have the kit, experience and practice to make the best chances of recovery possible (the golden hour).
Admittedly in the water we may need to aid the emergency services in moving the victim closer to them. However the greatest service an inexperienced rescuer can do is contact the emergency services as quickly as possible and get the victim safely (for all parties involved) to the surface. I do not want to come across as not supporting the rescue diver course, it is a fabulous course and a real eye opener to the participants. But a little knowledge can be dangerous, too much confidence very dangerous.
My advice to all rescue divers is to be humble, don't believe that a certification card makes you an expert. Practice, practice, practice and don't become the victim.