Tweaks just mental?

Some say that the effect some of the tweaks make are psychological. Let's say that it's a fact that some changes to your system are mental. What's wrong with that? We all know that we perceive sound differently. And we have personally experienced a situation with someone and had a totally different experience.

Just how mental is the whole listening experience? I'm not pretending to know, but I wouldn't be surprised if we find out that it's more and more mental. For instance, let's say I could make no changes to my stereo, but I could have the house alone for the weekend, I could toss my cares out the weekend for the weekend, play it at any volume that I desired (still no changes to the system). Further, I could reroute planes and vehicles away from my house, so that I didn't get low-freq interference.

I remember seeing a post where several audiophiles said that their best listening time was around 11PM and they attributed it to either smoothed power that time of night or more mental peace in their household. Hmmm ...