I think I understand somewhat better what you are talking about and have to say that I do not whether Yang Style has this particular practice or not. Let me explain, however, how the curriculum is supposed to work, as far as I understand.
You start with fixed-step and learn innumberable circle patterns and ways to transfer smoothly between them. With this background, you can train push-hands applications and engage in freestyle tests of push-hands technique, using no pre-agreed patterns.
You then do moving-step, which has three variations: straight step, cross step, and a combination. The combination step is known as the Da Lu (Great/Big Rollback), which has a specific and special hand pattern at its base, but which also has other variations.
Each of these patterns starts with a basic variation with fixed directions in which you can step. Each, however, can be varied so that the direction in which you step may be varied to a certain degree. With each of the moving step variations, you can engage in engage in freestyle tests of push-hands technique. These will involve whatever number of steps you want.