I dont use a deep fryer too make french fries I use a cast iron skillet.
I almost pulled the trigger on a deep fryer but held back because I would deep frying fire wood.
And yes I cook them two to three times and I learned this on my own through observation.
I also got tired of soggy fries so I started cooking them on low heat and then as I was eating them I put them back in the oil at high heat shock them and cook them the rest of the way.
Next comment is I make Belgium fries and I use almost exclusively mayonnaise instead of ketchup as a condiment.
Lodge makes a deeper skillet for frying chicken I have wanted for a long time.
https://www.lodgemfg.com/prodcat/deep-skillets.asp
I also use my cast iron dutch oven to fry food in sometimes but not if it is only going to be me.
Final thoughts.
Regardless of the instructions you will have to fool around with it.
Then when you think you have it right you wont because it depends on the potato variety and the age of the potato.
A good red potato cooked in beef tallow is fantastic.
Worth