Never get rid of compounds. You just bring the isolation stuff in during the heavier loaded weeks when it's more appropriate. The 15's are there for joint/tendon health anyway. You don't need to be hitting every bodypart seperately for this. The compounds will achieve that goal for you.
Plus, it's a lot harder to scale from the 15's all the way to the 5's with isolation stuff due to the lighter weights used. This hinders the submaximal progressive loading. Cut out two weeks and you invariably have the ability to make bigger weight incretments from workout to workout, which is said to be more effective for growth.