The point of the app is to teach you shortcuts, not to give you tutorials on how to navigate geometric proofs. Theres a reason we still have classes in high school and college that expound on important mathematical concepts and theories. While this app wont teach you necessary foundational knowledge, it will get you from A to B more quickly, whether that be during a timed GRE examination, when calculating supermarket savings, measuring ingredients, determining sales taxes, business profits, gas mileage, budgets, medication dosage, measuring the amount of wood or steel needed in a construction project, and so forth. These tricks make complex computations manageable for the every day person, and if it saves you a considerable fraction of time while doing any of the above-mentioned, then why not?