There's no reason for the average Joe to do forearm curls for basic physical fitness. While incredibly important, the small muscles of your forearm are used during practically every upper-body exercise as you lift, press, and grip weights and other equipment. If you're concerned you're not working them hard enough, ditch the curls and opt for jumping rope with a weighted jump rope, instead. In addition to taxing your forearms, you’ll benefit from a tough burst of cardio, too.
These are the muscles that run along your shins, folks. If you're wasting time at the gym working your shins (the muscle running along it is called the tibialis anterior, for what it's worth), you better be trying to recover from shin splints. Otherwise, it's not a thing.
Like the muscles of the forearm, no one's saying the tibialis anterior isn't important -- of course it is -- but as a small muscle group that's engaged during all lower-body movement, you're better off putting it to use when you run, jump rope, play a sport, or ride a bike.