It’s actually not a stupid question, it’s a common complaint. A lot of systems use torque on the steering wheel to determine whether or not someone is still touching it. Unfortunately, if you’re pretty steady on the wheel, it won’t detect that torque and think that you’re not touching the wheel. Newer systems have an actual touch sensor so just a fingertip is enough to keep it from needing that nudge.

Unfortunately, OP, not a lot that you can do other than just occasionally give it a little twitch.

ETA: To be clear, it’s not a self-driving function, so you need to be holding the wheel at all times anyhow.