As with any muscle group, there are multiple ways to target it, stimulate it and accelerate growth. It's having a clear understanding of these different ways which enables you to continue development, and ultimately take that muscle to the next level.
With your chest workout try to start with flies rather than pressing, the emphasis, in this case, was on pre-exhausting the pec muscles without involving the triceps. By the time you come to press, your pecs are already partially fatigued.
This isn't the only way to train your pecs, though, this is just ONE of MANY ways you can go about it.
I don't want you to get into the mindset that one thing is necessarily superior over another, instead view each training tool as a means of creating a new stimulus and opportunity for growth. Collectively, they can come together to create a multi-faceted training approach to ensure a muscle group is constantly worked through different mediums which are great for optimizing hypertrophy.
In relation to training your chest, here are 3 ways you can change up your chest workouts to change the emphasis.