I’ve heard that a ton of times, and the more I hear it the more I disagree with it. I get it, and in a true SD situation or competition, you should absolutely stick with what works for you unless you absolutely have to do something else.
But the notion of discard it if it doesn’t work is flawed. There’s been techniques that I didn’t think would ever work. My previous school taught lot of things my current school does. There were things I didn’t think worked until my current teacher made simple corrections. Timing, distancing, footwork, angles, and hand placement are all things that’ll easily make or break a technique. Get all of those things down, and the useless technique becomes practical and effective. This isn’t just striking; grappling is full of this too. I couldn’t do a fireman’s carry in wrestling to save my life for quite some time. Practiced it every day. Had I not seen it done in actual competition, I’d think it was a worthless technique to discard. Somehow something just clicked years later and I could reliably throw it.
Of course there’s some extremely idiotic techniques out there; I’m not talking about that stuff.