Many teachers will tell you that form work and pushing hands is all you need. But if you truly want to be proficient, skill is not enough. You need to be able to generate power.
The Chen syllabus starts with empty handed silk reeling movements. These movements are designed to get the body aligned and moving in the correct manner to receive, transform and express power. Silk reeling (chan ssu gong) is given this name because your movements should be smooth and continuous.
The curriculum goes on to pole shaking exercises, which build foundation and strength. The core exercises were developed into a form, demonstrated here by Grandmaster Chen Zhenglei.
The large pole gives you enough resistance to build up your strength without risk of heavy weights. Because of the inertia developed by moving the long lever, the harder you move it, the greater the resistance is. There are also other methods, which include the bang stick, weapon forms and medicine ball.
All of these training methods build up the body as a co-ordinated unit. This is is stark contrast to many western exercises, which tend to work each part of the body in isolation. When evaluating your exercises, how many of them work your muscle groups in isolation?
They may suit the aesthetics of your chosen martial art, but are they allowing you to generate power through all of your body? The benefits of internal training are that you are able to create a lot of power from very small external movements.