Usage patterns
〈場所〉に〈物〉がぎっしり詰まるto be packed tightly into a place
The bookshelf is crammed full of books.
〈物〉がぎっしり並ぶfor things to be lined up with no gaps between them
The dishes are lined up tightly on the table.
予定がぎっしり詰まるto have a schedule packed full of plans
My schedule today is jam-packed, so I don't have time to rest.