Well, there's ways to do what you want, but it really depends on how you got to the stage you're at. Usually it's very possible using an input variable and some simple formulas for each input, but what those formulas are, or if they're even needed beyond just using that variable, is probably different with each unique way of generating bricks.
One way might be to have a simple generator that makes slightly blurred, uniform brick patterns, which then gets details added with noise maps afterwards, so tiling the bricks doesn't result in repeats. Like, actually using the built-in brick generator, then adding fractal noise with an overlay blend, then slope blur, then dirt, or whatever...
So I think there's no one answer for such a generally stated question as this. It depends what else is going on in the graph.
