If you workout diligently, don't talk much and wait for the machines to be free, the training session should not be longer than 45-60 minutes. This is the time where you can give the most of you during the training session, and training for longer will barely give you any benefits. In fact, many people doing HIT training will be done in like 30 minutes, and they do get some amazing results. So it is a matter of how effectively you train.