Fatigue can creep up on you in unexpected ways. I had been in the edit room for over 24 hours, cutting sound for a TV show and a feature, both on a tight deadline. The scene I was working on was a 3-second establishing shot, and included streetcars passing each other. I was trying to sync the Doppler pitch shift of the sound effect (streetcar passing at 40 km/h) with the moving image on the screen, but couldn't get it right—when it's right, a kind of lock happens in the mind and the action comes together almost magically as a single event, and not as separate visual and aural cues. No matter how I tried, the sound was always out of sync with the picture, so I decided a break was in order, and took a walk up to Queen and John to get a chocolate bar and a coffee.
As I was standing on the corner waiting for the light to change, a streetcar passed by. And it was out of sync. I was shocked. The sound and image did not coalesce as one to me. I realized that the problem in the edit room was me, that no matter how long I tried to fit the sound to picture, I wouldn't be able to get it right that night. I was just too fatigued from too many long days hunched over a monitor. And I realized that if I did get it to look "right" that night, I'd probably have to redo it all in the morning anyway.
After a good night's sleep, I went in the next morning, put up the scene, and had it looking and sounding right in less than 5 minutes. Sometimes the most efficient way to get things done right is to stop trying, take a break, and come back at it later—especially when you've been at it longer than usual.