So if you implement the process near the end of the guide, then that can sort of work.
Basically, if you build a single game with multiple levels, then you are only limited the sound slots that are available. Meaning all treasures will use the same sound, and all ammo will use the same sound.
But, if you implement the trick where you make multiple separate, 1-level games, and name them in a way so the .exe file will read each game as a level, then you can change the sprite textures, enemies, music, and sound effects between each level.
It's a bit more difficult to use this trick, but it does work and can help create a more cohesive and varied experience.