Your cat's success at become mature (which includes not doing things that it wants to do but is not allowed) is a combination of you and him.
If you're currently unable to teach your cat something; then you haven't failed, your current method has. Improvise, adapt, overcome. Investigate why he's not getting it. Try to reinforce the point that he's not understanding. Tailor your method to the cat.
I've tweaked my escalation pattern for every cat I've raised. Not every cat is equal. Observe their behavior, find the flaw (= what you want him to change), then put the cat in a situation where that flaw becomes his weakness.
A great example of this is the first cat who I trained via escalation. He had a habit of meowing while sitting by the sliding door. I sprayed him, but he never really made any progress, he needed the spray every single time and I noticed that he was almost learning to never sit by the door. That was not the point of the lesson.
So instead of making eye contact with him, I started spraying him blindly. I reached around the couch and aimed blindly. Essentially, I started using his meows against him. Based on where the meow was coming from, I was able to pinpoint his location and hit him. Since I couldn't see him, I would be unable to hit him if he didn't make a sound. And that's exactly what I wanted. He was allowed to sit by the door, but if he made a sound, I would be able to spray him. It took a week or two for him to realize that not meowing would actually benefit him, and once he realized that, he stopped meowing.