Am I the only one who thinks hand signals beat radios on some jobs?

Had a young guy on the hook last month at a site off Highway 99 outside Bakersfield, and he kept squawking on the radio instead of using hand signals. An old timer named Ray who runs a 60 ton Link-Belt walked over and said something that stuck with me: "Radios break, arms don't." He wasn't knocking radios, he just meant the crew should know both cold because you never know when a battery dies or someone's mic gets stuck open. We started running a quick hand signal check before every pick that day, took maybe 2 minutes, and the guy caught on fast. Now I make it part of my morning walk through with the riggers. How do you all handle this, do you drill signals or just trust the radio?