Efficient Mass Storage
Double the chests, Half the space!
That's more complicated and less space-efficient than simply stacking chests next to trapped chests. And by building as high as he is you'd probably need to jump to reach the topmost chests. You definitely would need to jump to reach the topmost layer of signs.
I do this:
The topmost layer of sign is 3.5 blocks above the floor instead of 6 like in Kestrel's design. That means that all three vertical layers of chests are easily accessible from the floor, and so are the signs. The signs have enough vertical space on them to give a separate label for each chest, and in cases where you want multiple chests storing the same thing (very common) you only need one label. For example, the left-most column of chests are all designated for sand. There's no need to have three signs for that. Columns of chests that each have different things are simply labeled with one label per row on a single signs. For example, the fourth column from the left has from top to bottom: cobblestone, smoothstone, stone bricks. And with one third a many signs, and no redundant labels for chests that hold the same thing that means much less visually scanning around for the chest you want.
The wall behind the chests is made of jack o' lanterns, which generate more light and don't require an extra tile of depth or wasted space like torches do. It's also way more space efficient. Including the wall, Kastrel's "mass" storage system fits 23 double chests in a 9x5x3 space. Simpy stack the chests and you'll fit 27 double chests in a slightly smaller 9x4x3 space and without having to jump to reach the top or craft a bunch of stairs and way fewer signs.