Not all times of the day are created equal. Energy, focus, physical readiness, and mental acuity ebb and flow through the day, following predictable patterns. For the majority of the population, we begin the day strong, then have a slump around 6-8 hours after we wake up, then end the day strong.
There are significant effects of the mid-afternoon slump in hospitals everywhere. You're 3x more likely to be killed by your anestesia. Staff are 10% less likely to have washed their hands, causing infection rates to rise. Colonoscopies find fewer cancerous growths.