errr, yeah...let someone who knows how to properly lock apply a joint lock to you. If it's locked, there's not much room in your pain-wracked mind for struggle.
The best way to counter is to have practiced to the point that you "flow", feeling the lock coming and continuing in natural motion with it until you float into a counter or out of it. I've seen good artists flow through a dozen locks, one melding right into the next counter, before one of them finally gets the lock cinched.
Once locked in, it's really hard to get out no matter how tough you are. Many locks rely on the pain reaction to incapacitate an opponent.
Therefore, one must be careful of opponents who are high or inebriated because they don't have the same pain reaction. Of course, drunk or not, a broken arm kinda slows you down.
Locks are generally used to control the situation to prevent extreme harm. For that reason I prefer locks in general to kicking the crap out of someone. In extreme situations, it is easy to go straight for the sprain or break. It's all a matter of cinching tightly, feeling the opponent's motion, having the right angle, and knowing your control.
I trained for over 10 years in karate without ever learning real locks. Now, after 22 years of karate and 10 years of ju-jitsu, I consider joint locks one of the most effective weapons in my physical arsenal.
Different arts approach locks a bit differently. Absorb, evaluate, and apply what works for you.