If someone says “Couldn’t have gone much better” what does that mean?

Just thought it might be worth posting this. An old client of mine emailed me this question and here’s what I thought.

QUESTION
If someone says “Couldn’t have gone much better” what does that mean?
Is it , “it was great”?
I understand “Couldn’t be better” but the sentence above is using the third conditional.

MY ANSWER
“Couldn’t have gone much better” means that of all the expectations you had of a particular event, it was the almost the best expectation that happened.

For eg. if you were taking an exam and you had a range of expectations, perhaps scores of 45% 55% 65% 75% 85% and after taking the exam and getting your score back you got 83%, you could say “Couldn’t have gone much better”

We also say this after interviews etc., if the interview went well and in response to the question “How did it go?”