Once in a while, I clean my paint brushes with brush cleaner.
I take an old soup can, washed out really well, and pour in some brush cleaner and soak the paint brushes for a while. I wipe them down with a paper towel.
My normal brush cleaning routine is to use two different bottles of Testors Brush Cleaner. First one, then wipe on a paper towel, then the other, and wipe on a paper towel again. It keeps the second bottle very clean.
Of course, the Testors is only used with enamel paints, acrylic paints are washed off in the sink with water, or in a paper cup with water. Either way, all the brushes are cleaned with the paint remover at least annually.