Its hard to say. If you have the diet dialed in and are losing fat without cardio, then there would be no need to add cardio in. However, if you have a solid diet and it is movning slower than you would like, adjusting the plan is one option, or adding cardio would be the other. Just remember, you dont want cardio to be a crutch for an inferior diet. More so, you want to the diet to do the majority of the work and then use the cardio to push you that much further