My friend, an audio manufacturer, keeps his tubed DAC and tubed pre-amp on 24/7 during non-summer months, unless he knows he will be away from his house for a stretch. He is a proponent of 24/7, and says the power surge upon turn-on is harder on the tubes than 24/7 usage.
Assuming one listens to his or her stereo predominately on weekends, an alternative is to power up the non-power amp components on a Friday evening, and shut them down on Sunday night after all listening is completed.