I have books 1, 1.5, and 2 currently.
This year we are doing Grade 1 and just really starting a phonics/reading focus.
What I did for Book 1 and Book 1.5 is go through and put stickies at the top of the workbooks, separating all of the short /a/ pages, short /e/, short /i/, etc. (They are grouped all together in the workbooks, I'm not sure about Book 2+.)
That way, as our phonics program introduces vowels, I can pick and choose which practice page we want to do. Our program starts with short /a/, so I will start with those from both 1 & 1.5...then when a new vowel is introduced, we'll do some of those pages.
At the end, I'll let DD do the leftovers for review or fun/play.