وَإِنْ تَرَكَ رَمْيَ يَوْمٍ وَاحِدٍ: فَعَلَيْهِ دَمٌ.
Translation: Whoever omits the stoning of one day owes dam.
Omitting a full day of prescribed stoning also incurs dam. The text uses the same class of compensation for missing all days and for missing one whole day.
That does not imply the same penalty for a missing pebble or one of three individual jamrahs.