Not every type of monitor requires constant calibration, but it is nonsense to say that any professional colorist would leave it for years without calibration.How come I know professional editors and colonists in Hollywood that don't calibrate their monitors every week etc? They calibrate once and leave it for years.
I also know one guy who color graded for star wars films and he said his monitors weren't even calibrated at all because it doesn't matter
I worked at Company 3 for 5 years (not as a colorist), and our projectors were calibrated multiple times a week, CRTs were calibrated at least once a week, and Plasma / LCD / Dolby monitors were calibrated every couple of weeks. More often if requested by the Colorists. There was not a single high-end colorist there who wasn't extremely paranoid about the calibration states of their monitors / projectors.