What a great forum with many experienced and interested members. I see many of you are far more advanced in skiing and ski gear than I am, and it's nice to read your inputs.
I personally try to be knowledgeable and take care of my gear, save my money when I can, and be careful taking advice.
I am also an engineer and ski very seriously (for a flatlander.) Everyone has about the same conclusion, and here's my input from an engineering perspective:
1. You could leave your bindings set for 30 years and not affect performance one way or the other, at least in regards to the springs.
2. You could also adjust them back to zero after every ski day and not affect performance one way or the other, again only in regards to the springs.
3. The concept, however, of prolonging the life of a device such as a ski binding, or a component such as a compression spring, by lowering the duty cycle or "releasing the DIN setting" periodically, is indeed based on sound engineering. The principle is to minimize performance degradation, that is extending the life, by reducing the potential for fatigue, creep, and stress loading. It may very well be overkill for ski bindings though. Starting with the right spring is far more important, than how you use it in service. It's not an easy subject. Springs seem to baffle a lot of good engineers and designers, even predictable compression springs like these.
The springs themselves are not the nemesis. Someone above said skis will wear out before the bindings - well put. And within the binding design and component quality, several other components or functions will usually fail, or at least become unreliable, first. I check my bindings all the time, whether I've changed the DIN setting or not - I check them on and off the hill throughout the year. The best judges of how well ski bindings work - are skiers like yourselves. That's why I read forums like this. So thanks for a good topic and some good insight.