You ladies that have been greatly blessed with a larger family really do manage to roll with it quite well!

No matter what you do for homeschooling, it will certainly include full days, but I think you have some really good things going. One thing that jumps out at me, MomtoJGJE, is all of your dc are not beginning their new guides at once. I only am teaching 3 dc in 3 different guides, but our dc are on different units as well, and I find that to be very, very helpful! As of Monday at the start of our next week of school, here is where each of our dc are in their guides...
Wyatt - World History High School, 10th grade - Unit 18, Day 3
Riley - Resurrection to Reformation, 6th grade - Unit 26, Day 1
Emmett - Bigger Hearts for His Glory, 2nd grade - Unit 2, Day 5
Wyatt's schedule runs our year, just because he is the oldest, and he has always done a guide a year. So, when his 140 days of school are completed, the rest are 'done' for the year as well. This has worked wonderfully well! We have a day off each week, and that helps us catch up or rest and relax.
I have found I enjoy having different start times for each of the boys for their guides. It lets me really focus on a strong start for each of them. So, at the start of this school year, my focus was on Wyatt beginning his new WH guide. It was easy to put my time and energy fully into starting the WH guide because Riley was returning to RTR, and Emmett was returning to Beyond. We were in a good rhythm with both of them already, especially Emmett, as he was further into Beyond than Riley was into RTR.
A few weeks ago, Emmett finished his Beyond... guide, and it was time for me to fully focus on giving him a strong start in BHFHG. In about 9 weeks, it will be time for me to give Riley a strong start in RevtoRev. I may have him go half-speed for awhile, or I may not, depending on how it goes. By then, Wyatt will be near the end of his WH guide and smooth sailing, and Emmett will be further into BHFHG and doing quite well.
Anyway, I imagine you find the same to be true with the different places your dc are in their different guides! A real blessing, if you ask me!

Another blessing I see is that you have used HOD for awhile and as such, your dc are well-trained in how to follow directions (written/oral), how to do a CM style of learning, how to use their guide themselves for their independent things, and how to manage their time using the guide as a reference. Your older dc especially are reaping the harvest of the guides they have completed previously. This makes independence successful. If you were new to HOD and doing many new guides, beginning some dc half-speed would probably be a good idea, or stagger starting them would be another good idea - just so you have time to train dc adequately to be successful with independent things that are probably new skills to them.
Finally, just like you said, because your dc are all placed properly, your days are manageable. I'd never go so far as to say your days are all a piece of cake, as we all know how busy we are as homeschooling moms, and more dc do = more time/energy/responsibility. You choose a 'plan for it the best you can, but then roll with it' kind of good attitude, MomtoJGJE, and it just works. I know it won't be easy, but no one ever said motherhood - much less homeschooling motherhood - would be easy. It may not look the same for everyone, but the above 'blessings' I mentioned sure do make a difference. Thank you so much for sharing your plan here, as well as your good outlook on it! You are doing a wonderful job each day, and I think others need to hear how moms of multiple dc are having success in their homeschooling days.
In Christ,
Julie