Each week I run my class in North Sydney, located on Falcon Street at the PCYC. The main aim is to teach Wing Chun Kung Fu as best as I possibly can.
When I first trained, the schools I went to spent the first 30-45 minutes doing warm up excersizes and the last 30 minutes doing warm down exercises. For me, personal fitness and excersise does not increase your Wing Chun Kung Fu ability. fitness can be done on your own time for your own health. Perhaps run around the oval across the road before or after class. Time spent in class is one and a half hours of improving your ability. If you are going to a class where you are only spending 15-30 mins on actually Kung Fu, then you are not learning as much as you should - it will take 3 classes to get to the same level as going to a class that spends all the time on the art.
What we do in class is focus on the body, and how the body mass can generate power. Similarly we focus on Tendons and Joints for power. Doing fitness excersises does not help with learning this. What does help is focusing on the special power of the Sil Lim Tao form, and other Wing Chun forms, Chi Sau and other special Wing Chun activiites. The ulitmate aim is to gain Power, Speed and Technique.