Walls are known price limits. They can be used. The volume OOE is an approach that involves determining the time of a reversal quite precisely since volume leads price. In trading, taking the full offer of the market is not a known practice of "big money". Big money creates the walls and does not make money. Ping pong is an important recreation. Walls and ping pong are not like kind analogies. Ping pong has a strategy; walls are big money mistakes that parasitic traders (like me) take advantage of.
Trading is like being a detective. Recently you changed your alias, but you didn't change your syntax. Walls are very useful for watch ing the future views of "big money". This phenomena is called "telegraphing" or "tells" for short. Big money plays several "games" and they show the "future" in the Present. This trait can be called a "leading indicator" of price being traded in the Present. It is not what makes price move usually. But it does PREVENT price from traversing further. Read about the mistaken notion of "price drivers" which is gaining in popularity among the CW non traders (journalisits and writers). The wall is used by expert traders to carve turns to take the maximum full offer of the markets. For example, consider making an additional two ticks at the end of each reversal. Suppose further that the expert is trading 20 to 40 turns a day. Anyone can calculate that this is 20 to 40 aditional points per day on the ES e-mini. Read DH's estimate of his professional friends' performance each day or annually. 20 points times 240 days is much more than DH has ever seen anyone ever make. this value is just the additional precisiion result of using one's knowledge of the "big money" games that are played. Knowing whether "big money" is making a mistake or using a strategy is not something that is posted here every day.