Another version of this is not knowing the terminology.

My trainee asked me if I normalized my databases. I asked her what that meant. She was shocked that I didn’t do that!

After she explained, I said, “Sure, after I made the mistake of not doing so in 1970 and had to fight through the consequences. I just didn’t know that there was a term for it.”

The mark of an effective and efficient developer:
1. Your designs work
2. You identified the needed results, which may or may not be the requested results
3. Your programs work and are efficient
4. Other developers can read and maintain your programs

You need to develop something to show all of that if you are self-taught — either in your workplace or home.

A certification may help if you can pass one.