I only touch it when needed. I might use a tip pick every couple weeks, maybe, and that's only if I notice the tip doesn't seem to be holding chalk as well. I will burnish if it seems to mushroom a bit, but the tips I use (everest, kamui) seem to do that initially after installation and then are usually pretty good after. And I will shape if the tip starts to flatten out a bit, but that's after months of play.
Ideally, I barely touch it for the life of the tip. But I know guys that scuff, shape, poke, etc. almost every session, to each their own. I just figure the more I mess with it, the faster it wears down and the more likely I'll do something stupid and f@#$ it up...
Scott