I did 100 Easy Lessons with my older two. I’m now going through it with my son. I attempted it at least three time with my oldest, once when she was four, then five, but she wasn’t ready until about age six. Then we took a break in between and came back. She reads excellently. My second got it a bit quicker than my first. She wanted to do multiple lessons in the same day. Now I’m working through it with my five year old. Sometimes we do 4-5 lessons in a week. Sometimes we do one.
But he’s retaining it and is learning to decode outside of the program though we are only around lesson 30.