Both connected and separate madd involve a madd letter followed by hamzah. The decisive distinction is whether they are within one word or across two words, not the loudness of the hamzah.
«جَاءَ» — connected: alif and hamzah occur within the same word.
«إِنَّا أَعْطَيْنَاكَ» — separate: the alif is in one word and hamzah in the next.
«قَالَ» — natural: no following hamzah creates the same added cause.
When «إِنَّا» is joined to «أَعْطَيْنَاكَ», separate madd applies. In «جَاءَ», the combination is inside the word itself, so its classification does not depend on a boundary between two words. Identifying the structural cause is more reliable than memorizing a duration alone.