Al-Shafi`i's remarks likewise underscore the importance of whether a narrator agrees with other accomplished preservers or contradicts a better-established account. A trustworthy person's participation in a shared transmission does not remove the need to investigate such conflicts.
This does not justify accepting every additional detail merely on the ground of the transmitter being thiqah. The decisive inquiry is how well the person preserved that teacher's particular report and which version the relevant evidence favors.
Distinction: generally accepting reports from a trustworthy person is one matter; endorsing a singular contradictory detail without comparing it to better-preserved alternatives is another.