I don't know about English but in Portuguese is common even a native speaker to come across with a new word, but since Portuguese is a syllable-timed language most of the times easier to know how to write a word just listening to someone saying it, but in English I imagine that it's not that easy because there are a lot of homophones, and words that are written completely different the way its spoken, it kind of makes impossible to write a word without knowing previously, just like: threw, through, right, write
Does it make sense?