It applies to the period in algebra instruction devoted specifically to quadratic equations. It's a first step towards the concept of "multiply all combinations

It applies to the period in algebra instruction devoted specifically to quadratic equations. It's a first step towards the concept of "multiply all combinations and combine like terms", taught at a time when solving and factoring quadratic equations are brand new subjects. I don't think FOIL should be given much weight as some sort of eternal mathematical truth, but it's a useful stop on the journey.