My first solo was in a Slingsby Sedburgh somewhere around 1960 as an ATC cadet at RAF Weston Super Mare. Memories are vague but ISTR getting an AB certificate after a few more circuits, feeling rather chuffed but disapointed because this was the end of my gliding.
Fast forward to a stinking hot summer afternoon in Johannesburg in 1974, on my 3rd circuit of the day at Lanseria the instructor said make this one a full stop then opened his door and said the density altitude is getting too high for 2 in a 150 just do 3 more on your own and we'll call it a day.
Then he shut the door and walked off - just like that. So I did. No dramas, no warning, just do it.