The other three types of ripening do not result in karmic effect that will manifest swiftly. The first is ripening in the next life. For example, the effect of committing great evil, such as the five hellish deeds, or great virtue will definitely materialize in the next life. Second, the effect is certain to manifest but the timing of which is uncertain; it may take three or four lifetimes or even longer. Third, there may or may not be any effect. What could be the reason for this uncertainty in view of infallible karma? When a weak cause (or karma) encounters a strong antidote, causality may then be broken.
~Depicted from THE RIGHT VIEW - On Cause and Effect