The incremental position strategy is quite good, similar to having a forced stop-loss for yourself. However, there is an aspect of incremental position trading that you might not have thought of. For example, your stop-loss price of 4200 is also the liquidation price of the incremental position at 4200. However, if it reaches 4215, it might directly trigger a forced liquidation for you. There is a mechanism for early liquidation to prevent underwater positions, so compared to using full margin with a stop-loss in contract trading, incremental position trading effectively reduces the stop-loss.