I've experienced this over many years, sometimes it was the system, sometimes my mind set, other times the music and/or recording quality of the music chosen.
In recent years, system based dissatisfaction has been solely based on burn in of various audio parts (diy modder) or tubes, remaining mindful of this I no longer blame the system. Music chosen is not really a problem these days as I mostly stream. I sometimes make assumptions music chosen will engage, at times this is mistaken notion, it only takes a few presses on my tablet to change out the music.
The one remaining self doubt or system doubts is when playing unfamiliar new recordings in my Roon library. I may choose any number of mediocre to poor sound quality recordings consecutively and the doubts set in. I now ameliorate these doubts by playing a known high quality recording. While I still listen to mediocre to poor quality recordings, I now regularly mix in the known good quality.
When the greatest variability with one's audio system satisfaction is recording quality based you're in a good place!
I also can't fail to acknowledge one's own variability in mood, this will always remain. Making your listening room a special place or your comfort zone can be of great help here. And how about a little mind altering help via a touch of bourbon?