And to answer the question, “why bother with all that fuss with extension cords” — the answer is: to get rid of (or rather prevent) constructions like these:

As expected, 12 outlets turned out to be not enough (or rather, not everything can be plugged in at a single spot — sometimes the cable is just a bit too short), so the final (for now) addition arrived to catch up: a wall-mounted outlet block. They come in various configurations; I went with a more compact one that maximizes USB ports.