A blade coffee grinder uses rotating metal blades to chop beans inside a chamber. Running it for longer generally changes the result, but time alone does not select one precise particle size. Larger pieces and very small particles can coexist, which makes a measured brewing recipe harder to repeat than the dial setting might suggest on an adjustable burr grinder.
The practical issue is the distribution of particles and its effect on flow, extraction and sediment. Do not rely on a claim that ordinary use necessarily re-roasts the coffee: the main limitation is inconsistent grinding, even though extended running can warm the contents. Capacity, cleaning access and the intended brewing method also matter when deciding whether the device fits your routine.
If a blade grinder is what you have, keep the bean quantity and grinding routine consistent and evaluate the brew before changing several variables together. Avoid expecting it to provide repeatable fine adjustment for demanding espresso preparation. When comparing an upgrade, look at adjustment, dose handling and maintenance as well as price. This is a design-based buying analysis, without claiming a physical test or a guaranteed flavor improvement from a specific product.
The conversation
A good question can make a better brew.