We do spelling 3 days per week. I believe I read in Karen Andreola’s book, A Charlotte Mason Companion, that one of the ways CM did spelling was by writing the word very clearly on a small chalkboard, having the student say the word, look at the word, then taking the board away and having them spell it from memory. I bought some poster board and made my own flash cards using a black Sharpie. My ds is young enough that our word lists are rhyming words right now (i.e. light, bright, night, sight, etc.). Spelling is one of his favorite subjects!
We use our homemade flashcards with the selected list for that week on Mondays and Wednesdays. Then on Fridays, I dictate the words to him as he rights them down. In the 11 weeks we have been using this method, he has only misspelled one word during dictation, which I had him correct immediately. We use a different list each week, usually between 4-10 words, depending on how many I could find that rhyme.
I don’t know anything about IEW or Sonya’s Spelling Wisdom. I just know this has worked for us both academically and economically. Timewise, we usually spend about 5 minutes on the flashcards and about 5 minutes on dictation of the words. So 15 minutes a week has my ds5 spelling really well!
Hope that helps!