length of time they had been awake would explain why anyone would be off their game
Agree completely. The nature of fatigue is insidious and often difficult to recognise in yourself, especially in the wee small hours.
The nature of SAR is unpredictable and managing fatigue is essential - I always tried to have a nap in the afternoon if possible which helped enormously when the phone rang late in the evening or overnight, and yes, people did take the p*ss out of me for doing it but it worked for me.