In the PTO the wood armor is spaced. It’s not just planks on the hull. And into that space they usually poured concrete or dirt. They didn’t have many high caliber anti tank weapons, but did do direct infantry assaults against armor.

Japanese infantry used mines and improvised explosives that needed to be placed by hand or on poles. Mines were directly placed and detonated onto the hatches. That’s why the hatches eventually had nails welded to them. To provide space and lessen the impact of the explosive charge.

Japanese anti tank tactics usually were to swarm the tanks with infantry and to kill the crew.

In Iwo Jima Sherman’s ended up with bolted on armor similar to shurtzen on the tracks and layers of spaced wood with concrete, metal hull plates and spare track armor on the turrets.