The forced price adjustment is used for shorter discounts or increasing rates as it only deals with an exact number not a range.
e.g.  Easter long weekend which is 4 days with a min 3 night stay, the customer can stay 3 but you force the price equal to 4 days. Which is entered as a per night rate of $133.33.

Also, you can discount a 3 day stay e.g. stay 3 pay for 2.  If it is usually $100 per night then a 3 night stay will be a total of $200 which is entered as a per night rate of $66.67.