If continuity remains uncertain in a chain, what is the proper scholarly response?

Trustworthy Transmission, the Report of a Fāsiq, and Responsible Narration

• Treat any doubt as discontinuity and then label the report fabricated
• Treat two corroborators as obviating examination of hearing
• Investigate continuity and relevant evidence before affirming authenticity
• Regard simple contemporaneity as conclusively proving every connection