> The trace length has a negligible impact on latency.
Uhm, that is not true. If that was true, then your typical motherboard kept slots where they were 10 years ago, but they're getting closer to combat the increase in latency in other places. This is why HEDT motherboards have such layouts.
But just getting it close is not enough: M1 has higher memory latency than AMD and Intel SKUs.
How? It's the same LPDDR5 everyone else is using and it's on package not on "chip". The trace length has a negligible impact on latency.