Ozone only helps in situations where there is high bather load. If you are using the spa every day or two, then yes the ozone helps because it oxidizes some of the bather waste so that chlorine doesn't have to and that lets you turn down the chlorine generator and extend its life.
However, if the bather load is lower, say only using the spa on weekends with not many people and not a long time, then an ozonator will INCREASE chlorine demand so the chlorine generator will have to be on LONGER in between soaks to make up for the chlorine that is consumed by ozone.