One other thing to consider, rather than trying to complete all 4 levels in 3 years is that you can always get to a point that you skip a guide. If you have your heart set on CTC this year, you could complete it with the extensions at a slower rate. Then next year you could do RtR with extensions at a regular pace as well. Once your dd is in 8th grade, you would just complete Rev to Rev or MTMM depending on if you feel like she should "skip" a level. And then for 9th grade, you could do the WG guide as is. Since it sounds like your dd loves to read anyway, she probably could skip a level with no problem. I would consider skipping either Rev to Rev or MtMM since both are about American History. One other thought is that you could consider just doing CTC through WG only and not doing the WH guide since you are planning to move to something else for 11th grade. With that in mind, I might further consider stacking my schedule based on the classes that will be covered in 11th and 12th grade and weighting your schedule and electives based on what you will get from those other 2 years. I am sure you have a lot to consider
HOD is a wonderful company! Their programs are very full and rich. I can honestly say that each day is full enough. I have seen a few other people who have had their kids do 5 days a week to get them through an extra level by high school. I guess since my kids are on the younger end of the age range, I can't even imagine doing that! My kids would kill me! But I can see how, as my kids get older and more along in their guides, their days go much faster and we always finish within the time frame established. For us - fun, my work schedule and planned activities are what would prevent us from trying to do school more than the 4 days worth per week. Sure - we typically spill our week over 5 days but some are half days. I like the flexibility and break in a sense. If you try and do 3 levels in 4 years, at 5 days per week, you are looking at your year lasting 37.5 weeks long each year and that is with no extra days off. And - with HOD - my kids are covering way more school than most of their friends - those both homeschooled and those sent to school

. It gets to be a lot. HOD does an amazing job of making it balanced. But I would hate for your dd to get completely burnt out from all of the work.
While CTC is a wonderful level, since you already have RtR, I might consider sticking with it. I am not sure if your dd has read many books on the old testament or not. If she has covered ancients already, you could consider looking into having her read on her own over the summer some of the books from CTC spread out over several years. She could read the different books here and there in spare time. You said she is a voracious reader. So if she loves to read, then giving her the different books at different times creates interest. For example, my oldest has never completed Bigger. We didn't start HOD until two years ago and I put her in Preparing. She has read several of the science texts and extension pack books on her own. She has learned a ton from them too. I used to do a full day co-op (which I am excited to be dropping for next year) and she had to write a couple of reports that year plus put on a few presentations. Because the time period was modern history for one of those classes. she chose to read a few books from Bigger to complete those activities. Was I sad she didn't do Bigger? Yes, at first I was. But seeing how placement and the activities within the guide are the excitement of growth in each level, I am no longer sad. Bigger would have been too easy for her. I don't think she would have liked it as much as she did Preparing. Preparing was the first year she completed and all year long she kept saying how much she loved this or that. Then this year, when she did CTC, she again would comment on how much she loved this or that. Halfway through the year I asked her which level she liked better. I figured she would say Preparing because it was easier and the books in CTC were very challenging to read. She picked CTC! I was shocked. I think she knew she was completing challenging books and she was very proud of herself (along with just enjoying it because some activities were down right fun). We have 4 weeks left to finish up of CTC next year. I already know that because we will be studying Shakespeare, RtR will be her favorite

But who knows, I have feeling that once she gets to RevtoRev and MtMM, she will be saying those are her favorite

While IMHO each level of HOD is fantastic, the resources stacked with the activities and the balance of the day make it even better. I guess I say all of this to encourage you that you really don't
need to go back and do CTC. Can you? Obviously - you are the mama! But one last thought is that with WH, you will cover many of the same things that were covered in CTC. Differently? Absoutely. But the Bible in WH is all about old testament. If you are worried that your child didn't make enough connections now, then they will be making them then. Also - one final though - kids won't remember everything they learn anyway. Will they remember a lot of what they learned? It depends on the child. I do like going back through my kids binders (I keep all their stuff in a binder) and seeing if they can remember stuff about it. But even if your dd does complete CTC, there is no guarantee of how much she will remember from it or any other level for that matter. It is the love of learning that is being fostered here.
With your dd, if it were me, I would spend time praying about your goals. If your goals truly are to completely those 4 levels in 3 years, then you may need to make some sacrifices in other areas. I would just be prepared to do that. For me, my goals are to have my day be balanced and to be able to still do fun things during the day at least once per week. Plus, with working from home, sometimes I need to blow school off for a day or two because of some rush items. I need that flexibility in my day. This type of schedule - only doing school 4 days per week - gives me a much less stressed outlook and creates for a better happy homeschool mama.