Writing single letters teaches you the shapes. Writing words teaches you the blocks, which is the real skill in written Korean: the same ㄱ is tall and narrow in 가, short and wide in 고, and squeezed into a corner in 국. 54 everyday words, a few from each vocabulary theme.
A letter on its own gets the whole square. In a block it has to share, and how much room it gets depends on the vowel beside or beneath it. Writing 한국 teaches you something that writing ㅎ, ㅏ, ㄴ, ㄱ, ㅜ and ㄱ separately does not.
The same two passes as the single-letter drill: trace it with the guide on, write it again from memory with the guide off, then the guide comes back over your strokes so you can see where you went wrong before you move on.