I hope I don't open a can of worms here, as this has certainly been discussed to death elsewhere, but I don't have my students "warm up" or "cool down" within the confines of my class sessions.
While I have trained for several hours at a time from back-to-back classes, mostly in different schools, usually the classes I've taken were an hour. A few classes were an hour and a half, with the first 30 minutes or more dedicated to physical aspects (cardio and various fitness exercises). Thus on average, at best, an hour per class was spent working techniques, etc.
It's unusual, I know, but my advanced students train first. They warm up by themselves, at their own pace, in their own ways. After their class, they lead beginners through various warm-ups before the lower-level class. Then we all meet and begin working techniques, attribute development, etc.
I'm of the mentality that the instructor's time is at a premium. Professors don't give college students time in their class to go through notes and study; people come to the class to TAKE notes or take a test, without sample questions to get them in the mood. Likewise, I feel cheated when I take a 90-minute martial arts class but spend the first 60 minutes warming up. This is something that can be done outside of class.
Currently, I have to arrange my strength-training routine to match the classes I continue to take. When one instructor decides to have us do multiple sets of calf raises, squats and lunges as part of our hour-long warm-up (Mondays and Wednesdays), it'd be foolish for me to lift weights focusing on my lower body on alternating days (Tuesdays and Thursdays); I'd get no rest then. Likewise, in kickboxing classes that really work the shoulders, the teacher loves to exhaust us with push-ups; I have to do upper body weight-lifting at the gym on these days, so I can get at least 24 hours off to recuperate.
I suppose I should note that sometimes my classes are all sparring, sometimes a confusing mix of material, sometimes exclusively knife disarms, sometimes its combat scenarios in an alley, and a few times it was even doing combinations while wearing a business suit in the snow or a heavy backpack while walking on ice! Its hard to narrow down a fixed format for my classes when we try to adapt to the changing nature and possibilities of combat... blah blah...