That is not true.

There are some who plan around dates and there are some who plan around prices, and even if they plan around either dates and/or prices, they well be merely considering selling fractions of the bitcoin that they hold at the time that their selling criteria hits.

Sure there are some who have specific timelines.. but just because some do that does not mean that everyone does that or that it is even necessary to plan to sell large amounts of your BTC - even though surely I have no problem with ideas of planning to sell small parts of your BTC that could be either time-based and/or price based.. which I cover both of those kinds of withdrawal in my sustainable withdrawal thread... and neither of those systems have (by default) much if any intention to sell large portions of a person's BTC stash at any particular time, even though optionally they could be tailored in a way to sell large portions rather than selling in sustainable chunks..