Just thinking about this myself these days. I spent many many nights until 2am searching for the perfect thing, the perfect way before HOD. Always I wanted the thing that would cover it all and not leave gaps while it honored God and brought them to know Him more deeply. The ways I looked at doing this were many. The worry I spent was costly. My dh was ready to put them in ps at one point just so I would not worry. 
I was so busy looking for all the have to's I never thought about just looking for what would bring us peace. I would say peace is one huge unexpected HOD brought. It was something I searched for but could never find until I gave up all the ways I thought were involved in getting there and finally listened to God on what really mattered to Him instead of obeying my fears.The other really huge thing is HOD has really taught me how to teach my dd with cerebral palsy. Through HOD I have found methods that I can apply to other aspects and that has helped us tremendously.
My goal with her through HOD was to keep her progressing with the things that she can comprehend while teaching her the skills she needs. What I have learned is being on track with the things that she can know is not the issue to her success. It is really about keeping her on target with her skill levels. And that is not just about progressing through HOD guides it is more about progressing through life. Those needed progression of skills matter all over the place for her future. My mind set was more to over come those on the side and address the main event of getting the information. I see through using HOD that it is really backwards. We do not really teach our children much in the way of life skills when we do it that way. 
Truly what my daughter needs is to address learning what it takes to progress and to be willing to go through the steps to get there along the way. In short HOD teaches good work ethic in learning the little skills along the way that end up to the bigger promotion down the road. Thankfully this all comes within a time frame that I can correct and redirect my daughter. But I shudder to think how we would have ended up without HOD. I would have carried her the whole way and in the end I would have crippled her for life. Now I feel like we are learning a much better work ethic and she is learning that the skills must be learned to move on in life. Nobody arrives at a place of worth for free, unless they get there falsely, and to earn your way it is done a little at a time step by step. I think about how much that is going to translate in her life. So much more than "staying on track" of the history cycle ever would have benefited her.Another little aside I have seen is with my oldest. She has had her identity really all her life in helping my dd that has CP and is the same age as her. My oldest is very bright and has a kind heart. My two oldest have been together all their life. Not uncommon for siblings but in their case they are biologically unrelated siblings that come from across the world.
My oldest has always sort of mothered my dd with CP. She also has carried her a bit in life. In a good way but I could see it was clouding her. I had them all combined at one point because that is what I thought would be best for them and in all honesty it fit the cycle we needed. Last year I made the decision to separate them. I promoted my oldest to be more on target with her skills. She has been "alone" in the program she does. The other kids are all jealous she gets her own program all the time and gets to do everything first. What I have seen in her though is a real blossoming. She has some slight integrity issues I have seen completely disappear and replaced with some wonderful blessings. She takes pride in her work I have never seen her take before. The pride thing carried over and she pretty much jumped a year in both LA and Math. These are things I could not have guessed separating my kids into three different programs would have done. It was not what I thought would be best, but it was always what God knew would be best. Just took a lot of fighting with me to get me to listen. 
That leads me to the last thing I am thinking about today that was really unexpected. I never knew using HOD would teach me so much about listening to God when I do not see the complete plan or know quite how it will end. I am a big researcher. Before I do something I try to get it all figured out. I like to see how it is going to end before I even begin.
While my oldest was still in third grade I had all her high school and all the others planned out a few different ways. They were all ways that probably could have worked but none of them would have blessed us. I can see that now because the plan God had for us had not even been written. 
I wasted many hours, many weeks, months and a ton of time in general looking for something that God knew but I could not yet even see. Using HOD has shown me a lot about living more day to day and enjoying the ride, knowing God has a map and He is always leading. In the end His paths are always the best paths. Sometimes we search in vain.For I know the plans I have for you, declares the LORD, plans for welfare and not for evil, to give you a future and a hope.
Jeremiah 29:11
I know that verse but when it came to hsing I was never able to follow it. At simple glance perhaps I did not know what it meant. It's really a verse of trusting God and a promise I did not always understand especially when it came to hsing.
Praying Peace for you all in your hsing. And really hoping others will not leave me "alone" and post some of the unexpected blessings they have had using HOD in their hsing.
There are many other examples I could give but hoping others will fill those gaps in their stories. Hopefully we can lift each other up in sharing a few unexpected blessings. 