Clearance stock is reduced in defined steps rather than by continuous adjustment. The schedule is set by how long the item has been in the system, which makes the pattern predictable.
Inventory age drives the reduction
Retail systems record when each item entered stock, and clearance rules are usually written against that age rather than against sales performance.
Once an item passes an age threshold it is reduced automatically, whether or not it was selling steadily at the previous price.
Removing human judgement makes the process manageable across thousands of lines, which is why it is applied mechanically.
It also produces the occasional oddity of a popular item being reduced while an unpopular one launched later stays at full price, since only the dates differ.
Capital tied up in stock has a cost
Unsold inventory represents money that was spent and has not returned, and that capital cannot be used to buy anything else.
Older stock is also written down in the accounts, so holding it damages reported results as well as cash flow.
Clearing at a low price converts the asset back into cash, which is preferable to holding an item that may never sell at any price.
Steps are spaced to capture different buyers
A sequence of reductions extracts more revenue than a single large cut, because some shoppers will buy at each level.
Cutting straight to the final price would sell the same units to people who would have paid considerably more.
The spacing between steps is set long enough for that higher-paying demand to be exhausted before the next reduction lands.
Shoppers who track a specific item are effectively betting that it survives to the next step, and the retailer's schedule is built on the assumption that most will not wait.
Reduction days are often fixed
Many retailers apply markdowns on the same weekday, since the repricing work has to be scheduled into staff hours.
Shopping shortly after that point gives the best combination of a fresh reduction and remaining selection.
The day differs by chain and is not published, but it is easily observed over a few visits to the same store.
The floor is set by disposal alternatives
Reductions stop where the price meets what a liquidator would pay for the stock in bulk, since below that selling it wholesale is simpler.
That floor explains why items vanish rather than continuing to fall, and why the last markdown is often less dramatic than expected.
Anticipating the floor rather than the lowest imaginable price is the more useful way to judge whether to buy now or wait another cycle.