A profile is a snapshot of your device's color behavior at a certain point in time. To get the best results, your device should be in a stable and repeatable state. In theory, as long as your device never changes you should never need to re-profile. However, wear and tear on your device and environmental changes will cause color shifts over time, and re-profiling is the best way to correct this problem.
Liquid-crystal displays tend to be more stable than CRT displays because of their design. Each pixel is fixed in place rather than being "painted" by an electron beam many times a second. This allows them to be more consistent and color displayed on one part of the display has less effect on the other areas. Furthermore, digitally connected displays, such as those using a DVI or ADC connector, are more consistent because the signal is less vulnerable to interference from surrounding equipment. However, the phosphors do still fade, as will the bulb in the back-light.
For both LCD and CRT displays, the best way to determine how often to profile is with an accuracy test that can be repeated over time. To check the accuracy of your monitor with i1Match, go to the Help menu on a PC or the Eye-One Match menu on a Mac and choose "Start Monitor Validator". Follow the instructions to measure the colors that your display is outputting and compare the Delta E (a calculation of the amount of difference in color) from your original measured values. Your tolerance for Delta E difference will vary based on your industry and your needs, but we would usually recommend reprofiling if you have an average Delta E above 5.
Traditional cathode-ray tube displays will change over time due to burn-in, phosphor fading and diminished efficiency of the cathode and intensity of the electron beam. CRTs are also very sensitive to electro-magnetic fields and changes in power supply voltage. We recommend keeping speakers, motors and other monitors away from your profiled display to help reduce these effects. Variances in the line voltage supplied to your facility can also change the behavior of your display, so a line conditioner or uninterruptible power supply (UPS) is suggested.
In general, it is safer to profile more frequently rather than less frequently.
Printer Profiling applies to ColorMunki Photo or ColorMunki Design Only
Modern inkjet printers generally are very consistent if used and maintained regularly. You should make sure you always use the same type and brand of ink and that the print heads stay free from clogs. Follow these rules for when to profile:
Laser printer present a challenge because their output can fluctuate dramatically based on temperature, humidity, paper type and volume of use. If your laser printer offers a calibration mechanism, be sure to use it frequently. In a high-volume or less environmentally controlled location, you may need to do this every few hours.