What is the most important first inquiry when classifying an impediment?

Legal Impediments: Formation, Completion, Commencement and Continuation

• Can formation of a cause and operation of its effects be assumed identical?
• Must every nonoccurrence be attributed to lack of an eligible subject?
• Has the effect already arisen, or has the legal ground not yet matured?
• May every impediment be classified as a bar to continuation without analyzing its effect?