My amp is on everyday as I like to listen to the radio.
The amp is normally on when we watch TV too, not by choice, the majority of our viewing has been recorded through Sky HD and we can't view that unless the amps on, amp does the switching. It's kind of wasted on stuff like reality shows so I knock it into pure direct mode, I suppose it's better than the squeaky TV speakers.
The plasma is on everyday but we rarely watch HD through it anymore, this is saved up for the weekend when the projector gets fired up, we also watch the occasional Bluray as well, this is when the system really works well together.