Capacitors….Myth and Facts

So recently purchased a sweet gently used older model, based on the saves present on the drive it’s seen light to moderate use. So my question is after cracking this beast open, no signs of capacitor leakage or bulging. If it hasn’t developed at this point is that really a time bomb issue? Do they all go bad eventually or just high failure rate? Does leaving it unplugged when not in use keep voltage out of the system and reduce wear on the clock capacitor as it’s not constantly “filled”? The general consensus is always replace but I’m wondering if there are a large number of untouched units still plugging along.