I've been eating like a pig all year. I also took it easy for 2 months to heal a rib that stubbornly refused to stay in place. I've put on 15 lbs. I'm weaker and more out of shape, but am in the next category on the chart. Should I up my DIN?
I've noticed that you can have a ski come off your boot going absolutely straight, doing nothing untowards, just going through some frozen bumps/ruts. I've also had skis release when just side stepping up an icy hill with a little too much alacrity, and once while attempting to make a hard turn at about 45mph. That was very inconvenient, but in all honesty, maybe the skis were folding up on me and the release saved my legs (at the expense of my thumb).
On the other hand I caught a tip on the snow as the chair lift was leaving the station, and once when I hooked a tip on a mogul last year or the year before. That was a good release, as all I had to do was ski around a mogul or two, come to a controlled stop and climb back up for my ski rather than being tripped up and rag-dolling down to the bottom of the pitch.
After six years you should know. Bindings don't release all the time. Slow twisting falls are the hardest falls to release from; the bindings need to be able to resist being released from higher forces present in more dynamic situations. It doesn't take a lot of force to hurt yourself in an awkward position; it takes a lot of force to keep a ski attached when your land some air on an icy surface with edge set or just ski through ruts at 50 mph.
Where I ski, most skiers don't ski fast on the groomed runs, so most of them probably don't need more than level III. It's a level, a risk-acceptance level, not a skill level. There is no correlation between skill and DIN requirements, only between strength and ability to withstand higher forces. Your need to risk your bones with a non-release versus your needs to avoid loosing a ski may vary with what you are doing and where.