The node stores array at index 0 of the first output array, array is stored at index 0 of the second output array, array[n-1] at index 0 of the last output array, array[n] at index 1 of the first output array, and so on, where n is the number of output terminals for this node.
For example, assume array has 16 elements and that you wire four decimated array outputs. The first output array receives elements 0, 4, 8, and 12. The second output array receives elements 1, 5, 9, and 13. The third output array receives elements 2, 6, 10, and 14. The last output array receives elements 3, 7, 11, and 15. This is the expected behavior. If you remove one element from the input array there will only be 15 elements. The last decimated array will only have 3 elements (3, 7, and 11) since element 15 was deleted. Since the node will only return arrays of the same size, the other 3 decimated arrays will drop their last element so that all of the arrays now contain 3 elements.