Why six main guns can still support accurate gunnery

Would six guns meet the minimum needed for accurate naval gunnery?

Yes, six can support effective salvo spotting, though eight or nine guns would still be preferred.

Accurate fall-of-shot observation needs enough shell splashes to identify a salvo pattern. Six guns pass that practical minimum. Designers and gunnery officers would still prefer eight barrels, or nine in a three-triple arrangement, for redundancy and salvo weight. A three-twin heavy-gun layout is viable without presenting it as ideal.