How often is your system "good"?


In a recent article in Stereophile, the author wrote, "When my system is good, it forces me to appreciate artists and songs I'd never noticed before."
http://www.stereophile.com/content/schiit-audio-yggdrasil-da-processor-page-2#bQow2O0DxgbPdplw.99

My presumption is that the author meant that his system sounds better some days than it does others.   I think this is an accepted fact.  I believe my system does better early in the morning and late at night due to power constraints.  I have a voltage meter on one of my outlets and I feel better about the sound when the voltage isn't sagging.  

My question for readers here is how often is your system good?   And to what do you attribute the goodness of your system from one day to the next? 
mward
I work outside and when the weather and pressure changes so does my hearing acuity.  I wear earplugs often and that affects my high freq perception by making things seem bright.  
Power supply is definitely my biggest factor.   Turning off ceiling fans and other power suckers in the house makes for the best listening experience.
My system in always good. Sometimes I'm not. If I have a cold, the system doesn't sound so good. When I had a kidney stone it sounded terrible. When I was recovering fro open heart surgery, and I was on pain meds, it sounded great. My point is I've come to appreciate I am the greatest variable in how my system sounds
System sounds great when the wife is out. 

Simply put I can crank it to realistic concert levels or the sound of real instruments and that to me is where a high end system shines most - loud, dynamic and yet absolutely crystal clear effortless sound.
Just like you should never buy a car that was built on a Monday or a Friday, my system always acts like a lemon on these two days.  Rest of the week, its just fine.