Current theory, at least in many schools, is that children should be taught to read in two different ways simultaneously: phonetically and graphically. This is called Balanced Literacy. All the experts I trust believe it is a big mistake and is The Reason we have so many troubled readers.
Attacking a word phonetically or as a design -- this uses two completely different parts of the brain. It's NOT like going back and forth from hot dogs to hamburgers. It's like trying to pat your head and rub your stomach at the same time. It's stressful and exhausting. English words are phonetic objects and should be read phonetically. Some experts find room for a few sight-words in their theories. But I would suggest there's no reason for any sight-words. You simply introduce a complexity that is not required.
I recently published a piece called "Reading is easy. Illiteracy is hard." Easy to find. It contains seven helpful quotes from various experts. All of them stress that children should easily learn to read by first grade, or age 7 at the latest. There are many schools that now basically waste the first two years making children memorize about 100 sight-words. At that point, instead of being readers, these kids are effectively on the way to being functional illiterates. The NAEP scores show the devastation created these wrong-headed methods.