In order to standing locks to be effective... you have to understand what that means and what your drills are.
Most people will agree that one of the most valuable strikes is the jab. But, less than half of the jabs thrown actually snap the other guys head back. Does this mean that jabs are not effective? Is a jab only successful when the other guys head snaps back? Is a jab only effective when the other guys head snaps back? Yes, the jab is successful and effective, even when not snapping the other guys head back, because it is doing lots of other things as well... measuring distance, interrupting his breathing, interrupting his flow, giving him a problem to deal with, hiding a follow up movement, causing the other guy to move, or to freeze, taking the initiative, picking his hands a guard up...
Let's start with the drill, grab the guys wrist and twist like this. Really, that is a drill to learn an effective way that the wrist needs to be twisted... not necessarily, the most efficient way to apply the twist. Its a good way to see and feel how twisting the wrist, captures and effects the elbow, then the shoulder, then the spine. I find that through doing these drills, I can refine the way that the joint needs to be isolated, and the specific directions that it needs to be moved in. I also get to refine how to keep the other guys structure broken and off balance. When I go to the more effective, BJJ/MMA/wrestling version.... I find that if I can apply the same refinements, with respect to the other guys wrist/arm it becomes a lot easier to be successful. I see many of the same refinements show up in lot of different versions of different locks.
Let's go back again to the drill. Usually the drill involves the other guy reaching / punch for you... you get offline, blending with their extension, securing your grab and then applying the lock. Getting offline is a very good skill to develop, all by itself. Depending on the distance, you can either set up a nice hook to the head or kidney / liver with the off line movement. This part of the drill alone can be practiced and you should learn to make adjustments to hit various targets with hands, elbows, knees, feet. This movement can also be used to take the back, with some sort of arm drag being added in. Is the drill for getting the wrist lock not effective? Even though it is opening up all kinds of other opportunities for me? In my opinion, if I don't see and practice those other opportunities... thats on me, not the drill, the kata or the art.
Let's go back again to the same drill. When we do this in class, we do as above, catch the wrist and apply, the other guy taps and we move on. But, really he taps because you achieved the position and he stopped moving. Most of the time, if I apply a standing lock and then hold my position, you can just walk in the right direction to unlock the lock. That happens, because I stopped moving. This is an important thing. If I always train this way, I will always stop and the other guy can keep moving to escape and or reverse. We in the TMA side do this to ourselves, by always stopping there. We need to keep it going further. See, all the things we do to get there are important and correct... breaking their structure, taking their balance, isolating the joint.... it all makes getting to the position possible. But, we also need to practive maintaining those things as the other guy moves. When he moves, you can move in such a way that you keep his structure broken, you keep his balance and his joint isolated. But only if you practice this.
Let's go back again. Is this only effective and successful if I do as above... applying the lock, and maintaining it indefinitely? The truth is that they can counter and they will counter. In boxing, you are destroying your opponent if you are landing 1/3 of your jabs and 45% of your power shots... And these are all proven effective techniques.... Remember when I talked about how this was about learning to get to the spine through the wrist? If I can catch the wrist, and effect his spine, to momentarily disrupt his structure and or balance... that gives me a ton of openings.... even if it does not end in the classic wrist lock tap out that I got in class, doing a drill. The trick here is to understand what you got, (broken structure and off balancing) and what you don't (just lost grip on his wrist)... don't go after something that is no longer there, take an option that is there... (strike, throw, take the back....) Even if you only get him to react to your attack, you are taking initiative... he is reacting to you instead of you reacting to him. You need to let go what is gone, and take what is presented, to keep him reacting to you.
The success of these techniques is based on what you take away from them and how deeply you look. But you do have to get past the idea that it is only successful if it looks like the kata.