From the perspective of the stock and bond rebalancing strategy, a relative proportion relationship is artificially set between the asset proportion. For example, if the stock rises too much, it is necessary to consider reducing to increase the proportion of bonds. That's the equivalent of predicting that the stock has gone up too much and can't go up any more. If assets go up a lot, depending on the time scale, there are a lot of factors to consider when mechanically applying a rebalancing strategy. For simplicity, it's better to let what can go up continue to go up.