I agree writing a variety of software will have similar base ideas, but still, having a good foundation in a topic doesn't make you an expert. I've barely used

I agree writing a variety of software will have similar base ideas, but still, having a good foundation in a topic doesn't make you an expert. I've barely used Java, but if I had to I could learn enough to write it pretty quickly, that doesn't mean I understand at all how JVM and Java's GC works, or what a factory is.