As a junior planner in BA's Eastern Routes division in the early 1970s I was tasked with developing a 'passenger preference model' based on the loads on 6- 5- and 4- stop routings by day of the week. My mathematical hokum impressed the managers but I didn't believe a word of it, with just (max) one flight a day on any given route, you took what you were offered. And Thursday was the busiest day because the fares were higher on Fri-Sat-Sun (surprise).