Most gyms work off a 3/1 system: a buzzer rings to start each round, goes off again to end it. My suggestion to you would be to train for what you are going to fight. There is an insane desire these days to do too much and too many guys leave their fight in the gym. You want to enter the ring prepared to go as many rounds as you are scheduled to go, all out, if need be, and to have 1 minute to recover. Train for your fight.