Let's face the fact certification agencies made a decision long ago not to put expiration dates on the cards. So we all have a bunch of card that only expire when we do.
At the same time I think we all recognize that most, if not all, dive operators are now asking us the date of our last dive. More than one year with no dives and most operators will require us to complete a refresher course. A few operators have now moved this to just 6 months. We can all debate how liberal or conservative the length of time should be, though I'm sure most of us have seen more than one dive ruined due to a diver with rusty skills.
I subscribe to the philosophy that I owe it to those with whom I dive to keep my skills up-to-date so as not to be the cause of a preventable problem or otherwise ruining someone else's dive. I can only hope other divers will be conscientious enough to return the favor.
In my opinion, I think the overall safety and training attitude among divers has generally been on the increase. I believe there are a lot of divers who would voluntarily participate in periodic refresher training if it was actually offered, if it was convenient, if it was affordable, and especially if they perceived it to be of value to them personally.
Maybe I'm missing something but right now in the refresher training department there is pretty much only a single product offered for sale. Seems the training agencies may have some untapped potential to offer other kinds of refresher training considering the plethora of initial training that is currently available.
I plan my dive trips pretty far in advance like many other people. To me part of getting ready for a dive trip means booking air, hotel, rental car, dive operator, etc. It also means making sure my gear is in order... do I need to purchase anything, get anything serviced, test or inspect anything, decide what to bring, what to leave at home? It also means making sure I'm physically and mentally prepared to dive. Right now if my gear isn't in order I have lots of options on how to correct the equipment side of the equation. Seems to me if the problem is actually on the human side of the equation the entire dive community would benefit from having a few more options.