Everybody is right. The standard procedure is to fry twice. First you blanch, you can use a lower temp so they don't brown too much. Then drain and let them sit and finish cooking from their own heat. You can even do this hours before if you want. The second frying can be fried at 350 or a bit higher and should only take about 4 or 5 minute, tops.
Many places that cut their own fries blanch them up in the morning and store them in bins in the refrigerator and use then fry them up as needed throughout the day. They can even be stored overnight. Careful not to overcook them the first time because they will get mushy and fall apart during cooling and storing.
Older oil browns them better. New oil will not brown as well. Some places add a few cups of the old oil to the new oil to help the browning of the second stage. I've seen some places keep a fryer at 325, with new oil, for the sole purpose of blanching. Then, as the oil gets a bit older and dirtier, it is strained and put in the regular line fryers to use for the food orders.
Older potatoes will brown fast and may never crisp up. In my restaurant, I dreaded the late winter when we were still using the last seasons' potatoes. They would be brown and sogg, and there was nothing you could do.
There are a lot of factors that go into a good french fry.