This kind of app is actually a fun way to keep your brain active, especially with the timer and quick challenges because it pushes you to think faster instead of just solving at your own pace, but I feel like tools that also show how the solution works can make a big difference when you get stuck on something more complex, for example https://edubrain.ai/long-division-calculator/ explains long division step by step so you can actually see each part of the process instead of just getting the final answer. That makes it easier to understand where mistakes happen. Mixing something like that with a quiz app could really level up both speed and accuracy.