I have given up on benzotriazole. Using a ferricyanide rehalogenating bleach (and then re-fixing) after dev and fix has allowed me to use old paper with quite pronounced fog, with very good results.
This is a great way to save old papers if you normally add density or even flash the paper to give the bleach something to "eat".
But with lith papers so hard to come by, and so wonderful with even badly fogged papers... don't trash it or waste it if it liths, someone will pay for it!
And lord, Brovira is a freaking fabulous lith paper. The matte is pretty damn glorious, the gloss really has some balls, so to speak - just punchy blacks and contrast.