this isn't entirely true. Boost pressure as well as timing need octane equally. Both increase cylinder pressures and create heat to an extent, both of which require octane to keep pre-ignition and detonation away.
That's understandable, but wouldnit be safer "generally speaking" to run more boost with a conservative amount of timing, rather than lower boost and higher timing? I would think the inconsistency in fuel quality would have things skew to the lower timing being 'better'. Granted, if running ethanol, this discussion changes dramatically.