Context, folks, context. The OP wasn't asking about Gitzo-style knob locks, but rather about twist locks (think bathroom faucet).
FWIW, I much prefer the twist locks as they give me more confidence in their ability to secure the legs than flip locks. That said, both styles need occasional adjustments, as someone indicated earlier, with an Allen wrench.
As for Eric's negative experience with the Gitzo 3541 knob locks, I have never had a problem. Always safe and secure on this end.