I created these for my students over the summer and I had my students working on these since the beginning of the school year during word-work.
My students are showing mastery of all the spellings I've taught so far because they are able to practice chaining everyday.
My chaining activities are designed so that they can be color coded for keeping track of all the materials and to differentiate the skills that need to taught.
For ex. you can have Unit 1 skills on yellow and instruct your lower group to only use those chaining cards. While the rest of the class can work on green (Unit 2) or pink (unit 3).
I hope this will be as helpful to your students as it has been to my students.