flexing on din is absurd when you think about the variables and how they bring it up or down, like longer BSL bringing it down.
even on a brand new binding, (at the higher end of the scale) being a whole point higher on the scale is still considered within the norm for the machine release torque for your details, so variation up and down a bit is totally normal and to be expected to get the release point you need/want, especially if your risk tolerance between all mountain skiing and park/bc skiing changes.
Also, fatigue on bindings will eventually mean you should be setting them higher if you were getting them regularly tested but, you can kind of sense when this is happening anyway and adjust accordingly, so I would be unsurprised at people on old bindings riding them higher than they technically should.
It is always worth making sure your forward pressure is right and your boots aren't too worn before adjusting your din though.
My feeling is that bindings should be designed with more discrete din adjustment screws so you have to know/research what you're doing to adjust them.