Constantly at a medium level -before, during and after a project. I don't worry about tiny details or slight messiness but the floors, equipment etc is kept relatively swarf free. I see no point in making a lathe or mill squeaky clean every time it's used. I woulnd't get anything done. Do I vacuum and wipe it down? Heck yes -constantly. Do I worry about a handful of chips in the tray? Heck no.
I never use compressed air for cleaning. Just use vacuum, (3 in the shop for easy access) broom (3 in the shop), whisk broom (one at every machine) and heavy paper shop towels. Mop the floor once a week. Once a year, I devote a couple days to a thorough organizing and cleaning/inspection of the machines with oil changes etc.
When I was working we cleaned our machines just before the end of the shift. Compressed air can be a safety problem. For safety we sweeped the area around the machines. Nothing like cutting up a hardwood floor with chips trapped in the soles of your shoes. In school we had to wipe the machines down as well to make the shop look good.