>>If you already understand it, you don't benefit from solving more quadratic equations. You benefit from doing whatever the next step is. You just burn time pl

>>If you already understand it, you don't benefit from solving more quadratic equations. You benefit from doing whatever the next step is. You just burn time plugging things into (-b +- sqrt (b2-4ac)) / 2a. And you learn the wrong lesson, which is that you have to get it exactly right, rather than why that's the equation in the first place. As some one who works in Data Analytics, I can tell you many people lack the ability to plug things into a formula properly, many have issues with even simple approximation and back of the envelope calculations. I wouldn't say, practicing this is a bad thing. By the way if you think this is wrong. A little scaled up version of this is what is tested in current day interviews. Asking people algorithms is basically testing their ability to remember a heuristic and their ability to plug in numbers and demonstrate mental acrobatics.