«وَقَدْ يَسْتَمِرُّ التَّفَرُّدُ فِي جَمِيعِ رُوَاتِهِ أَوْ أَكْثَرِهِمْ»
At times singularity continues among all the transmitters of a report, or most of them.
Picture a chain in which each transmitter has only one identified student who carries this particular report. Singularity then extends over several consecutive generations. Later some transmitters may acquire multiple students, so only the early majority of links remain isolated.
The precise distinction is that absolute singularity is identified by isolation at the pivotal original point, while continuing isolation throughout every generation is one possible stronger pattern, not its necessary definition.
Noting many isolated links is also not, by itself, a complete judgment that the chain is authentic or weak.