Ladies,
This is a great question, and one that we have definitely pondered!
If you do happen to have a 5 year old in LHFHG, and you use a guide a year every year it is possible that you will finish the HOD cycle by the end of your child's junior year. It is good to keep in mind that it will be a rare family who will not be touched by hardship, transition, or life's surprises and is truly able to keep the pace of completing a guide a year every single year that their child is school-age. So, it is often a huge blessing to have a bit of wiggle room already built in for you. Many families do not have this wiggle-room and would desperately love to have it!
I mention completing the guides, because families may in their quest to stay on the guide a year plan, omit whatever was not finished in a previous guide to move on to a new guide the next year. This pattern can leave a child feeling overwhelmed and unprepared in starting a new guide, so often it is better to stay-the-course and carry a guide over into the next year to finish, which can also draw out time spent in a guide and is something to consider.
With these thoughts in mind, I wouldn't make a specific plan to stretch the guides out as plans can often change.
If your child and you as the teacher are able to complete a guide at full-speed, I would definitely do it. You will know if you ever need to shift to half-speed or need to slow a guide down. For those with combining scenarios, we will sometimes slow a 5 day guide down to 4 days a week to allow a younger child to stay with an older child, so this is one scenario in which a bit of slowing down is often recommended. Another time that slowing down is recommended is if a child is on the youngest side of a guide and seems to be struggling a bit with the workload. Or, if a family is large or has time-consuming health issues, we may advise slowing down a younger child for a time.
One other time that slowing down a 5 day plan to a 4 day a week pace would be if other children in the family are using HOD guides that have them on a 4 day a week plan and the family desires all kiddos to be on a 4 day plan. However, if the child being slowed down is on the upper end of the age range of a guide, we would not recommend slowing down for that child in this situation.
Another thing that we would not recommend, would be to plan to use another company's program in between your HOD programs simply so your child will not run out of HOD programs before he/she graduates. We often talk to many parents who have switched to something else and then returned to HOD only to discover that their child lost the momentum and progression of skills that we were carefully building from one HOD guide to the next. When they returned to HOD there was much reteaching of forgotten skills that were not focused upon in their year off.
Using HOD guides in consecutive order will gently and progressively move your child toward the needed skills for upper level work.
Of course, you are always in the driver's seat and may choose any program you desire for your kiddos from year to year.
I just wanted to share a bit of perspective on reasons not to panic and overplan what you think may be a gap year that in most cases will never actually come to fruition.
In those rare instances where a child begins the HOD path as a 5 year old and truly completes a guide a year every year through high school graduation, you have a couple of options. You may either graduate your child early, as he/she will have completed his/her high school requirements, or you may use that final year of high school to further pursue studies of interest, apply to colleges, retake the ACT or SAT if desired, begin a program such as College-Plus and start earning college credit while still in high school, travel abroad, work in missions-related work, take some courses at the community college, do an apprenticeship, etc. etc. The possibilities are endless! From our perspective it is better to have a year left to pursue these things later than to plan on stretching coursework out in the early years. Leaving yourself wiggle-room to stretch as the need arises is a wise option.
Blessings,
Carrie
As she is at the youngest end of the guides, would we be "skipping a grade" if we went straight through the HOD guides at full speed? 
so I thought I would respond. I don't think you will miss a guide, but you will be finished with the guides quicker. Maybe you could stretch the last guide out to cover 2 years. Your daughter could even take some college courses online or at a local community college.