Al-Nawawī records that ʿAṭāʾ b. al-Sāʾib experienced confusion later in life. Consequently, transmission heard before that change must be distinguished from transmission heard afterwards.
Al-Nawawī separately records negative assessments of Yazīd b. Abī Ziyād from several critics; al-Nasāʾī’s wording مَتْرُوكُ الْحَدِيثِ is more severe. For Layth b. Abī Sulaym, he reports the majority’s criticism on grounds of اختلاط و اضطراب (confusion and inconsistency), together with differing views about whether his narrations should be written down. ʿAṭāʾ’s late-life change, Yazīd’s explicitly adverse critic judgments, and Layth’s unstable transmissions must not be reduced to an identical grade of weakness.
The methodological consequence is specific: reports from one narrator may be evaluated differently according to when a given student heard from him. Knowing the transmitter’s name alone is insufficient; the particular route and timing of audition can matter.