The Moldau, Re-Listened
Too much routine can blind you for important things. In German, we call this "Betriebsblindheit" (roughly translatable as "business blindness"). It's the primary cause for having retrospectives in agile settings - a team that works very well can easily descend into self-complacency and "this is how we do it around here" mentality, blinding them for both chances for improvement of problematic behaviours and opportunities for amplification of good ones. Never stop observing, never stop reflecting.
I'll use a musical example. Bedřich Smetana's piece "Vltava" ("The Moldau") is, for the best of reasons, immensely popular and often performed. So often, in fact, that a certain fatigue can settle in. I've personally heard it so many times I thought I'd heard it all. How wrong I was. At some point, I stumbled over this performance, and it's new. The tempi, the way the orchestral groups are coordinated, the utter transparency of the melodic lines were simply striking. Granted, there are little glitches in the timing here and there, and the violins' forest nymphs motive is submerged in the woodwinds, but do take it in and revel in it. I can't stop praising this.