Right quick cuz I'm headed to bed

, but I face that issue with both my boys as well. I don't think it will matter, really, though because if you look at the sequence, they will still cover all the time periods. It will just be broken up differently.
For instance, my Caleb will use Rev to Rev and the not yet released Modern guide in 9th and 10th grade, both with extensions. Then he will do the Geography guide in 11th and the World history in 12th. He'll miss the last two high school guides, but that's OK because they will cover the same time periods as Rev to Rev and the new Modern guide. We might have to beef up a bit for high school, but since he falls within the extension range, I kind of doubt it.
Josh will wind up missing the very last guide. He'll do the Modern guide (the one to follow Rev to Rev) in 9th. Because this will cover the modern period, I'm not worried about missing the last guide, which also covers the Modern period.
Am I making any sense?

I would be hesitant to skip a guide because the guides are soooooo much more than just the history period. The skills built on each other incrementally, so I would be afraid that if I skipped a guide, my kiddo would miss the skills that guide taught, and therefore be frustrated in the next guide.
HTH!
Living the adventure, blessed to be schooling 3:
Cub 15 MTMM with extentions
Crawdad 11 Preparing
Taz 6 her own interesting mix
Have used and loved: LHTH, LHFHG, Beyond, Bigger, Preparing, CTC, RTR
http://ourhomeschooltravelingzoo.blogspot.com/