I wipe off the exterior and apply new grease to the lugs after every shooting.

I completely disassemble the bolt and clean and re-lube the insides once a year. Every year in the winter I detail strip and clean every rifle, so I do it then. It is kind of a drag since I then need to spend an entire day in the spring re-zeroing every rifle, but it makes me feel good if every barreled action is taken off and cleaned once a year.