I check my brakes in conjunction with my pull test function check of the hitching after backing onto the hitch. I do not rely on a visual check or the sound to determine if I am safely attached, though I do listen for the sound and look it over after the jaw trips. I lift the front jacks a few inches off the ground (hydraulic in my case, so one is all the way up and the other is a little bit elevated), keep the chocks in place, then manually apply the brakes with the brake controller while applying a very small amount of accelerator in forward to pull gently against the hitch and chock. If I am hitched and the brakes are working, I should feel the resistance. If I am not hitched properly, the hitch will disconnect and the trailer will drop at most 1 - 2" if I don't stop before the king pin comes free. Better than dropping on the bed rails. It has never happened, but I still do this every time I hitch. Since I have a factory installed brake controller, I also see the controller output on a display in my dash, so I have a secondary wiring continuity check as well.
I'll point out that this will not replace the need to periodically check the brake pads, etc. It is only a check of the braking system function, primarily the wiring and controller.
I have on occasion applied the brakes manually with the controller at low speed when I had some reason to doubt everything was right, but I do not do this routinely. You have to be on the right road, speed and traffic conditions to do this type of check.
one_strange_texan
Currently between RV's
Former 5th wheel owner (Montana 3402RL)