I generally find the numbers printed on pasta boxes for cooking time far too high: I'll set the timer for a minute below their low-end "al dente" time, and when I taste one it's already getting too mushy. I decided to run a small experiment to get a better sense of how cooked I like pasta.
I decided to use Market Basket Rigatoni. [1] It's a ridged cylinder, and I measured the ridges at 1.74mm:
And the valleys at 1.32mm:
The box recommends 13-15 minutes:
This is a house brand pasta from a chain centered in a part of the country with a relatively high Italian-American population, so you might think they'd avoid the issue where Americans often cook pasta absurdly long:
I boiled some water, put in the pasta, and starting at 9min I removed a piece every 15s until I got to 14:30:
Here's the minute-by-minute, cut open so you can see the center of the noodles:
My family and I tried a range of noodles, trying to bisect our way to the ideal cooking time. I was happiest at 10m15s, but ok between 9m15s and 11m30s. Julia thought 9m45s was barely underdone, while 11m45s was barely overdone. Anna liked 10m30s. Lily didn't like any of them, consistently calling them "too crunchy" up through 10m45s and then "too mushy" for 11m0s and up. Everyone agreed that by 12m45s it was mushy.
Instead of 13-15min, a guideline of 10-12min would make a lot more sense in our house. And, allegedly, the glycemic index is much lower.
My mother and her siblings grew up in Rome, and I wrote asking about what they'd noticed here. My uncle replied "my bias is that Americans are wimps for soft pasta" and the others agreed.
I tried using a cheap microscope I had to investigate, whether there were interesting structural differences, but even with an iodide stain I couldn't make out much. Here's 3min:
And 7min:
And 13min:
On the other hand, the kids and I did have fun with the microscope.
[1] We called these "hospital noodles" growing up, because when my
mother had been in a hospital for a long time as a kid (recovering
from being hit by an impatient driver while crossing the street) they
had served Rigatoni as their primary pasta shape.