I don't know about individual set but I've played a 3.5 hour match. Last year was a struggle. I wasn't playing a lot and not practicing at all with a new baby so all of my matches and sets were close. The longest one I remember was a 5-7, 7-6, 13-15 affair that lasted 3.5 hours. Needless to say I felt that one the next day.Played yesterday.
1st took an hour and a half.
Managed to play another 45 minutes before the lights switched off (it was at night). Didn't even finish the second.
Calories burned: 1700 (my opponent was wearing a Fitbit).
Today I'm tired!