How many loci do you need for a full 52-card deck?

About 18 with triples (three cards per image) — or 26 with pairs (two per image).

* PAO cuts the palace to ~1/3: ~18 loci for 52 cards instead of 52. *

The compression sets the locus count:

• Triples: 52 ÷ 3 ≈ 18 composites → ~18 loci.
• Pairs: 52 ÷ 2 = 26 composites → 26 loci.

So a modest palace handles a whole deck. That's the payoff of PAO: without it you'd need 52 loci (one per card); with triples you need roughly a third as many.

Go deeper:

• Memory sport (Wikipedia) — competitors use PAO/Dominic to compress the locus count.