نَجَحَ الْمُتَعَلِّمُ. نَعَمْ، نَجَحَ بَعْدَ جُهْدٍ طَوِيلٍ.
The learner succeeded. Yes, he succeeded after sustained effort.
The second clause reaffirms the initial success while adding how it was achieved. By contrast, in “The learner succeeded. He had mastered his lessons,” the second clause might answer the newly implied question “Why?” and thus function more evidently as explanatory resumption.
To distinguish the relevant reasons for faṣl, ask whether the second clause strengthens the same assertion or supplies an answer newly invited by the first. A clause may contribute secondary nuances, but the principal discourse relation should still be identified.