One of the things I had to repeatedly correct with my students when I was teaching English, both in writing and when speaking, was how to use "and". Despite what I'm sure are years of studying English grammar rules, students seemed to think that you should put "and" between each noun that you were stringing together in a sentence. For example, a student would say, "I have been to Italy and France and America and Canada and Hawaii.*" No matter how many times I would explain to students that you only need to say "and" between the penultimate and final noun, most would keep doing this persistently. I'm pretty sure they wouldn't do this so consistently unless their early teachings taught them incorrectly or their teachers failed to correct them.
I won't miss correcting this persistent mistake, which should never have occurred in the first place had people been taught correct grammar by a native speaker rather than a Japanese teacher of English who implanted all of his or her errors in the language into the students.
*Because, you know, Hawaii isn't part of America in the minds of most Japanese people.