As a traveling consultant in the mid 90s I used to book trips that overlapped with a Saturday night stay to save a lot of money. I would book a 2 week roundtrip Houston to Louisville ticket and the a weekend roundtrip Louisville to Houston in the middle of the other one. The Saturday night stay was put in place to gouge business travelers and after a while they had to drop the practice because too many people were doing what I did.
One trick that I learned from my boss was to book the trip for a Sunday return, then show up Saturday morning and get put on the standby list. NOBODY flies from Minneapolis to Toronto on a Saturday.