The methodology is living with a component in a system over a period of time.
I have often overlooked this myself. A controlled test can't account for this since it is based at a "point in time" which can be influenced by several biases including how an individual was feeling that day.
Same principle applies subjectively to auditioning equipment in a showroom. Something that might sound great for 20 minutes might not be something you want to listen to over 3 hours, a week, a month or year.
Your statement is extremely pertinent 2X6.