As noted earlier, the reality is that any of these strategies could simply be decided on the spot rather than being articulated up front in a WPS. There's nothing necessarily different about what is going to be done, simply because it's detailed in a WPS ahead of time.
However, reacting in the moment to whatever is going on is, almost by definition, not actually a plan. And unfortunately, given the reality that the time for negative adjustments is going to be when markets may be most volatile or outright in frightening decline, trying to react objectively in the moment may not be likely. Instead, if the situation demands action and there is no plan up front, the next step is likely to be an emotional one—which risks derailing long-term goals even further (e.g., selling out of markets entirely in the midst of a decline).
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Accordingly, the real point of having a WPS is that it is a true articulation of an actual plan about how to deal with a market decline, as it specifies exactly how cash flows will be generated, where withdrawals will be taken and—when paired with an IPS— what investment changes may or may not be implemented in response.
In other words, just planning to make adjustments if/when/as the markets do whatever they do is not actually a plan, but having a WPS to follow actually is a real, actionable and implementable plan.
At the end of the day, having a WPS is about managing behavior. From that perspective, it appears to be a very effective potential strategy, because it appropriately sets expectations and makes it clear how to act in the face of uncertainty. In fact, it can potentially help to alleviate stress in the face of market volatility simply by making it clear when it is time to worry and act versus when it is not.