How much is the length of the dj in the middle of the ballroom dance?

Tianjin cotillion hall, morning practice field is six and a half to eight and a half, morning field is nine to eleven, afternoon field is fourteen and a half to sixteen and a half, evening field is twenty to twenty-two, are two hours. The dancing is an hour of ballroom dancing in the first half, fifteen minutes of disco and cha-cha-cha at intermission, and forty-five minutes of ballroom dancing in the second half.