I was about to hi-jack the Zhai Weichuan wu/hao promotion thread but thought there could be more discussion if I started a new thread.
A couple of short clips
Teacher Fang, Wu/Hao tai chi. I like Fang's movement, very compact. His wu style:
https://www.youtube.com/shorts/ULNK2x0E-xs
But he also carry the principles from his wu style into his Yang style, also very compact.
https://www.youtube.com/shorts/Apt2YH-Pn38
If you watch more of the clips from the same series, you can see understand more clearly the roundness of the movements and how his hands seem to move together, or communicate which each other.
IMO, this resembles how Yang style should progress, from the large movements designed to open up the body and the limbs, to the small and compact. Many yang stylists never progress to the round and compact, so they only keep releasing the energy all of the time. But if the art progresses in this manner, you still keep YCF's "song-kai" or "relax-release", while continuing the movement's circulation, which means that you keep building up the energy instead of just releasing it. This way you can also feel and focus more on the internal movements, which again, builds up your energy better.
I am reluctant to use terms/words as energy or qi, the use of them in these arts release too much associations... But it's something you learn to feel. If you study the large frame and smaller frames, you should be able to feel the difference.
From a martial perspective, you build up a more compact power using the whole body, a power that preserves your movement/energy. A good illustration, putting "compactness" into context, though from a Xingyi POV in the following clip. You should really watch the whole rest of the clip starting from this point: https://youtu.be/qXdH2r8dZHs?si=laX7OTjL0sZC8A95&t=246
In traditional Wu/Hao style Tai Chi you also often start with larger movements and have exercises for opening up the body. In Xingyi, you often start with large and strong movements, but progress to small and soft. Nowadays in most of TJQ and XYQ schools people seem to only learn and focus on the large frames and never really progress to the more advances levels. I wouldn't even call it "advanced", but what many older teachers would consider the "real" and most important practice.