No break in procedure will add 500 more rounds of barrel life. No break in procedure will shrink 1/2moa groups to 1/10moa groups. Breaking in can help reduce fouling, and improve ease of cleaning. That's really all we're talking about.
In general, barrel break in should have purpose.
For me, the idea of a barrel break in procedure is to 1) fire lap the grain structure at the surface of the bore, then 2) impregnate copper into the remaining pores of the bore. To accomplish this, I clean with a copper solvent after every round for the first 20-25 rounds, then only with a powder solvent until 50-100rnds, starting at every 5, ending every 10. From then on, I only clean the bore with a powder solvent, and never use a copper solvent until groups start to open up.
After that, generally I can clean once every 400-500rnds, which entails 2 passes with a nylon brush, and about 3 cycles of one pass with a wet patch followed by 3 passes with a dry patch - then the patches come out clean.
For a 460 S&W, if I'm honest, I wouldn't bother, I'd simply shoot and be merry.