It depends on the situation...
for service rifles over the course, I'll run a wet patch down the bore using a Dewey service rod and muzzle guide, then leave in open case inside the trunk, while I'll drive home.
Then I'll finish the bore with more wet patches and dry it, light scrubbing with toothbrush to remove carbon / residue from exterior, then wipe with oily cloth.
For any hunting or sighting in, just wipe the bore and exterior.
Once a year (winter due complete detailing and lubing.