The use of articles is the biggest mystery of English language. No native speaker can concisely explain where to put them and where not. Apparently the rule is that it just has to "sound right".
I think that's true of most rules. Almost no native speakers can come close to explaining anything, but experts in language studies generally have very specific rules.
And by the way, articles are not the biggest mystery imo. Coming from a country that speaks Hebrew, which is a language that doesn't have the very "to be", explaining what that verb does is much harder. In Spanish things get even funner, since there are two version of the verb "to be", and which one is used depends on the next verb and has to be memorized.
And don't get me started on tenses. In Hebrew, there is no such thing as "I went" vs "I have gone" vs "I have been going" vs "I am going", etc.
