Insanity, menstruation and postnatal bleeding are discussed as legally significant impediments in relation to prayer. The ruling depends on the relevant part of the prayer period and on the specified legal conditions.
These examples show that, in recognized cases, the Lawgiver may remove a particular duty even though the person did not perform it. Removal is not the same as performance.
The discussion cannot be generalized into a claim that any difficulty or interruption during a prayer period automatically cancels the duty. Named legal impediments must be distinguished from ordinary hardship.