1. I felt that the rice for nigiri was more cooked through when served over more aged fish, and less aged/fish with more texture were served with rice that had more al dente/toothy bite to the grain of rice. The chef also seem to pack it more densely for the less aged ones vs with more aged fish the rice seems bit loose.
2. For nigiri part of the meal, the chef seems to serve more aged fish first and progressed to less aged ones; this seems be the trend as there were a few items out of the order.
I don't have a lot of experiences, but my recent meal at a reputable place in NYC made me think about this experience a bit more in depth. I wonder if these observation has any truth to them, and if so it would be interesting to learn about the reasons behind them.