I'm not familiar with in n out. Most chain burger places cost their fries in chemicals to make them crunchy longer. A natural cut fry becomes unappetizing like 10 minutes after it's out if the fryer.
There are trade offs with each way.
One is "cleaner" or maybe purer
One has a better customer experience
they single fry, not double fry. This is the classic way fries are fried and actually the big innovation that made McDonalds fries so famously good. Double frying results in a crispier and better tasting fry at the cost it being worse for you. Also let's them transport them easier en masse
they go light as fuck on the salt (some locations I've been to didn't salt at ALL though that may have been a mistake during a rush), to the point they provide salt packets to salt your own fries, which many people don't do.
I think they might also fry theirs in peanut oil like 5GBAF do, but I'm uncertain on that front.
Personally I think their fries are some of the better ones but you gotta salt em
I worked McDonald's when I was 16 (37-years ago 😢) and we didn't do that.
Worked a famous bar-and-grill in college and they taught us that, but we called it "blanching". You could damn near serve hour-old fries, still crispy.
They're fried before they're packaged and sent to the franchises who do the actual end frying
Blanching is the same as frying but instead of an oil you use water and then also sink or rinse it in cold water to quickly halt the cooking. Doing that with fries would ruin them, but I don't think it's wrong enough if a term to care. If someone knows what blanching is and you say you did it to your fries with oil they'll get what you mean