One of the better ways to check on your car brake pads is through the Brake Master Reservoir. This is where you top off your brake fluid. As long as your car brake system has no brake fluid leaks, and you don't top off your reservoir too frequently, it is a reliable gauge on how worn out your brake pads are. This is advisable for those who have difficulty identifying brake pad indicators or calipers. It is also advisable to make this checks only on Brand New vehicles or those with just Newly Installed brake pads.
There is really no need to top-off the the brake fluid reservoir once it goes below the maximum level line. You really need to top it off only when it is close to the minimum level line. When the fluid level is close to the Minimum Level Line on the Brake Fluid Reservoir, it is best to have the brake pads checked on how worn out it is. Again, make sure first that your brake system has no leaks. Some leaks may not be visible from the outside, especially for those equipped with brake drums. So, in having your brakes serviced or checked at this point could also tell if the system has a leak.
If you always maintain your brake fluid levels to maximum, it will not be a reliable gage to see how worn out the brake pads are. If you observe that the fluid level goes down abnormally after just a few days or miles of drive, better have your brake system checked for leaks.