You can be assured that the design engineers intended the printer to be power up 24/7, and have incorporated the necessary firmware routines etc to allow that to be the best way to operate the machine. That is true of the consumer models too, but keep in mind the 3880 is a commercial model. Probably the vast majority of working 3880's are never powered down.
Then, I wonder why the Engineers decided to include an ON/OFF switch on the printers. Will you please list the link (or other documented reference) regarding the information (above) regarding "what the Design Engineers intended.
I have used 4 different models of Epson printers over the past 8 years, the latest being the 3880; and never have I had the pleasure to actually read any specific information published by Epson regarding leaving the Epson Printers ON all the time
The ON/OFF switch is there to allow it to be powered down before it is moved or when maintenance is to done!
To put my comments into perspective, I am retired but worked in operations and maintenance of telecommunications equipment for almost 40 years. High reliability for the operation of electronics equipment is a topic that I have extensive professional experience with. That said...
The cost of electricity to run a printer 24 hours a day is virtually nothing. Big printers take up perhaps 50 watts when printing, but only 5 watts when idle. If you have relatively expensive electric power, at say 10 cent per KwH, it will be 2000 hour before it costs 1 dollar. That's 3 months. Actually, that works out to $4.38 per year for idle time power usage.
Second, the stress of powering up an electronic equipment is far greater than that of allowing it to simply run. Voltage and current peaks when the power is initially applied are the primary cause for failures in that type of equipment. (That assumes fans are functioning and filters are cleaned at appropriate intervals.)
There are potenial advantages to power cycling such equipment, but they are all probably best limited to when there is an obvious indication of some need. Particularly modern equipment that use microprocessors to control devices can benefit from a CPU restart. With some equipment the only way to accomplish that is a power cycle. With higher end printers it can be assumed that the "Reset" button on the panel will work. Lower end printers might benefit from going through the self test routine, which for example might include nozzle cleaning. Ideally a user would do nozzle cleaning as needed, but if they don't then an occasional power cycle does it for them.
All in all, if you perform appropriate maintenance there is virtually no benefit to powering down a printer every day or even every month. And obviously while I originally said there probably is no harm done if it is turned off, rest assured that while the harm isn't great it most certainly does happen and is far greater than any harm from 24 hour a day operation for an entire year.
Incidentally, I have three computers in front of me, and the uptime for each is 141, 167, and 209 days. The 209 figure would be time to the last power failure, the other two have had hardware maintenance done on them. I have on occasion over the years had personal computers that went more than 400 days between reboots.
