My 1st instructor, Master Yun Kil Kim, would give us one heck of a workout. Class was anywhere from 2-2 1/2 hours long. Warm-ups & stretch for a half hour, Basics for an hour, *a 2 minute break for water*, then we'd work on poomsae, sparring or both.
I trained there from age 14-17. I thought all TKD classes were that hard & that long. Wow was I surprised when I got to my next dojang.
*We had a pizza place next door to the dojang. In the summer, the front & back doors of the dojang (no A/C). The guys at the pizza place would leave pizza then couldn't sell (due to burning or something) & pitchers of ice water for us in the alley for our break. We inhailed (sp?) it in 2 minutes & kept going.