Cheap brake pads and rotors might fit on a vehicle, but you could be stacking the tolerances against yourself. Some brake part manufacturers do not make parts to the same tolerances as the original equipment manufacturer. It might be a few millimeters here and a less expensive there, but it all adds up when the parts are installed on a vehicle.
A brake rotor or disc manufacturer may combine part numbers if a rotor has a similar size to another vehicle. One rotor may have a diameter of 250mm and another rotor might have a similar design and the same bolt pattern, but it is only 243mm. The manufacturer may combine the part numbers for the two applications. 7mm may not sound like a lot, but it could mean that 3.5mm of the brake pads go over the top of the rotor. This will produce the wear pattern as seen below.
The same overlapping wear pattern can occur replacement brake pad manufacturer does not match the shape of the original friction material. The change to the shape can happen if the manufacturer does not have the engineering information about the vehicle. But the new pads will fit in the caliper, but just barely due to the wider tolerances.
If you combine the wider tolerances of the brake rotor and pads you could be stacking tolerances causing a potential safety issue.