Below the Minimum 's "One of the ways in which GURPS prevents abuse is by limiting a trait’s net modifier to no worse than -80%. For example, an advantage with a base cost of 50 points will never cost less than 10 points, no matter how many limitations one adds. However, sometimes an advantage is so extremely limited that it becomes hard to justify charging even 20%." resembles Modifiers and Minimum Costs from GURPS Psionic Powers.
This exception helps explain the Rapid Healing situation presented in the Basic Set's "Designing Entirely New Advantages".