EMTs and other first responders: is a medical alert necklace also useful, if someone doesn't want to wear a bracelet?

Specifically, a necklace on a normal chain, where the patient has tucked the actual medical alert pendant under her shirt rather than wearing it over her shirt? I guess the broader question is whether you routinely check for alert jewelry even if it’s not immediately obvious at a glance. Would a wallet card in addition be useful?