There are 2 school of thought. One is that turning electronics on and off is taxing on the switches and components. Two is that thing will wear out faster if you leave them on (LCD screens for example). Either way you are producing more heat and electricity by leaving things on all the time, with more possibility for wear as well. Internal battery life is the same either way these days. I am inclined to think that Keyboards are a little different than computers and should be turned off after being used for any length of time, at least at the end of the day.
