Spoilers ahead for A Quiet Place Part II (2021).
When Emmett and Regan are making the journey toward the harbor, Regan walks barefoot (as their family has seemingly done out of necessity since the onset of the crisis – a major plot point in the first film) while Emmett walks freely in work boots.
This contrast is made very clear during one particular scene: when Emmett and Regan are walking across the suspension bridge, and the shot switches between Evelyn and Regan in their respective treks, focusing on each of their bare feet on the ground – and Emmett's steel-toed shoes in the background. For this reason, I'm reluctant to believe that this was a directorial oversight.
Perhaps he was less experienced than the Abbotts in long journeys? Possibly more confident than Regan in the power of her amplifier? Or maybe (doubtfully) Cillian Murphy didn't want to walk barefoot. I'm not necessarily looking for an in-universe explanation; just an evidenced one.