My studio equipment is ON when I'm around, what means from 17:00 till 01:00 almost every day.
Displays losing brightness/contrast seem to 'warm up' while the instruments internal temps get a little higher. You should be able to re-adjust the contrast-poti during operation.
Modern components don't lose quality while on, as long as they are not electronic-tubes. In fact most defects occur while switching equipment to ON.