Ladies,
This is a terrific thread, and one that is full of such wisdom.

This kind of very fruitful discussion is exactly what I was praying would result as we announced our decision to write guides through high school. We desire for you to know that we will partner with you as you seek the educational path the Lord sets before you and that path will look different for each family, even though we may be using the same guides. This is because in a literature-based approach, coverage in specific subject areas is not always as clear cut as subjects overlap, allowing credit to be awarded in a variety of ways and areas.
With the scope and sequence that we have shared for future HOD guides, we see 3 options for families. The first option would be to use a guide a year every year. In this option, those who begin in the middle or upper age range of our guides, would complete a guide a year and make it through all the guides. In this option, those on the youngest age range of our guides will finish high school at age 17. Either way, by the time kiddos reach the geography guide, all subjects in the guide will be high school level material, meaning high school credit can be given for the work.

How much credit is given, depends on how you are choosing to award credit, but traditionally 120 hours of work equals one credit. This is roughly equivalent to 160 forty-five minute class periods. There are other ways of awarding credit, and the time allotment route is not a strict requirement as every child works at a different pace, but this gives you a guideline.
So, in option 1, whether an 8th grader or a 9th grader does our geography guide, the guide will be high school level material. It is at that point that you can begin counting credit for high school without any modification to the guide and could graduate your child early, after finishing our 4 high school level guides if desired. These would be listed as the child's 4 high school years on the transcript. Most states have a minimum age requirement for graduation (or a compulsory age for attendance) and a credit requirement for graduation, but I haven't yet seen a state that has a "number of years" of schooling requirement. So to see what your requirements are, be sure to take a good look at your state requirements.

Typically, as long as all credits required by your state have been accumulated (which in most cases is a less rigorous requirement than the colleges want to see on transcripts) and the work is high school level work, and your child meets the minimum age requirement, he/she can graduate. I graduated at 17 and headed to college when I was barely 18. I was just young for my grade. It worked well for me! I also have a niece who is in a grade ahead of her age level in the public school and will graduate a year early. She will only have attended 12 years of school, counting kindergarten. So, it is not as uncommon as you'd think.
If you do not desire to graduate your child early, then you have many options as to what to do with your child's final year should your child finish our set of guides early. However, it is likely that year would be an extra year not needed on the transcript, since your credit requirements will have been met in the 4 previous years. This leaves the final year open to pursue an apprenticeship or other career related move, work on college admittance, focus on life skills, do mission related work, etc. The pressure should also be off a bit, as the SAT/ACT should have been taken by then. But, if needed it would allow an additonal year to retake the SAT/ACT more than once.

This extra year would be at your discretion.
A second option we see as a path at HOD is to stretch one or more of the younger guides out as needed to accomodate your student's needs, thus traveling at the student's pace. We would recommend this slowing down option only if your child needs to grow into the skills in a guide, but not as a means of just slowing down in order to fill time. This will leave the long-term plan of guides flexible and will allow you to customize your plan as you go. The sequence of guides we have planned could potentially give you a year of breathing room, depending on the age of your child, to use to adjust to your learner's specific needs or to adjust for life's surprises, which is a welcome option. The path leading up to high school also meshes well with the high school path, allowing students who may not get to all of our high school guides to still get be able to get their high school credits in many areas without such major tweaking.
A third option is to keep your older student in the extension range throughout the guides, using our beefing up suggestions on the board that I've already shared to help you award high school credit. This would work as well, as you customize the path needed for your child, but use the HOD guide as your spine or core for as many subjects as possible each year. This would give you a needed plan into the high school years, allow you to combine with younger siblings potentially if desired, allow you to target your family's specific goals as needed, or allow you to have a main plan of action from which you jump off to accomodate an older student. In this option, your child may not get to all of the guides that are specifically "high school level", because you'd be beefing up the younger guides for high school instead. It is also possible in this plan, for a child in the extension range, to move forward if needed by skipping over a guide to get a better placement for the child. We would usually only recommend skipping ahead a guide for a child in the extension range who fits well on the placement chart in the guide ahead, or if the child was combined with a younger sibling and is now ready to go forward on his/her own, or if the child was previous in a guide that was too easy for him/her.
You can see from these 3 options that a high school plan could look different for different families. We have never been a one-size fits all curriculum and will continue to offer the options above to find the best fit for each family.
I know this can be a bit overwhelming, but I want to encourage you that options will hopefully give you confidence that you can do homeschool high school and that we will be here to partner with you as we travel the path together.
Blessings,
Carrie