If you turn it off at the mains, it will stop in the middle of whatever it is doing, and it might not be in the right position.
That's the main problem, but some models also track how long the printer has been off. When switched on it decides whether or not to go through a cleaning cycle based on how long it has been switched off. If you disconnect the printer from a power source you effectively disable this function. The printer will then go through a cleaning and purge cycle when powered up again even if it was out of use for only a very short time. This won't cause any errors. It just needlessly wastes ink.
Bob Smith
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