Epson says this about power on/off

I just had the head on my 9900 replaced, and while the service guy was there, I asked what was good for the printer/what was bad, how to get the most life out of the printer etc.

He said the #1 thing was to never turn off the printer, leave it on 24/7/365. He told me, and this is an officail Epson repair guy, not a sales guy, that when you turn the printer off, the heads move off the parking pad and it can lead to clogging. Now this might only be for the 9900;7900;4900 and your printer may not work the same way, but I thought it was interesting.

The other thing he told me was to print on it at least once a week, even if its a test print. To let it sit more than a few weeks can cause clogging problem.