If you have never experienced a brake failure, how do you know they will actually lock before the air is gone? I suppose it would work if the gear snapped down quickly. I have one plane with orifices in the gear air lines and the gear come down slowly. But it has a separate systems. Air tanks don't cost that much these days.

But that is a good idea to minimize the risk of tying the two systems together. Learn somethin' new everyday.