G'day Megan,
"There was a time (1930's?) when spot landings were a requirement for issue of a PPL"
It goes back earlier than that. I found this in a Digger's service records who was accepted into the AFC in 1918 ...
"Climbed to 10,000 feet, remained there for at least 15 minutes, after which he will land with his engine stopped, the aeroplane first touching the ground and coming to a halt within a marked circle 150 yards in diameter."