Glad you enjoyed the post, I went with the spike of 14 because of either the portion size required to eat 250g of carbs in one sitting or simply the quality of carbohydrate that would allow you to eat that much in one meal.
That kind of meal plan obviously isn't for everyone and is a very bodybuilding/macro-counting oriented approach to minimising average blood sugar while maximising carbs consumed. The most efficient balance for a low Hba1c would be to eat low carb with all carbs in one meal ie: the best case scenario.
I feel the margin of error would be impossilbe to calculate without the statistical data of a few thousand type 1 diabetics and seeing as most don't eat like this and have a largely varying diet of different kinds of carbs/fibre and eating habits the error could be greater than 50%. A better way to look at it would be that the above calculated average blood sugars are the absolute minimums(best) blood sugars you can achieve with your particular kind of meal plan where the lax in your own discipline or other unforseeable complications account for any higher average levels.
I know from my own experience of eating only 70-100g of carbs a day, about 30-50g each at breakfast and dinner (2 meals) with only meat, cheese and leafygreens at lunch my fasting blood sugar was around 5 and post meal was usually at 6-8(avg 7) at 2 hours so mathematically: ((4x7)+(20x5))/24 = 5.33mmol/dL which translates to a theoretical Hba1c of 5.0% and my actual Hba1c was 5.1%!!! thats an error of only 2% (I did have the odd hypo and the odd hyper)
So I imagine with very consistent control you could easily see an error of only 10%
So I'm going to try replicate my last Hba1c with 1 meal of high carbs; allowing for a higher spike of 9 which conveniently gives the same result
But like I said this kind of thing isn't for everyone, I know there are those who struggle to keep their levels below even 8 or 9 due to other complications. I imagine that this fasting approach could help those who are stuck at Hba1c's of 6 or 7 who need that extra little change to join the 5% club. Or for bodybuilders and athletes who need the high carb count but don't want to damage their bodies just to achieve it.
EDIT: formatting
Your HBA1c is great - mine is normally good and I have been diabetic for over 25 years now and I am a woman whose had children, and my daily routine can vary mainly as a result of having had children
. I only eat about 140g carbs a day at 3 meals (I've always counted carbs and more by chance have ended up on a lower number of carbs). I don't regularly exercise, though I am fairly active and I wonder whether that is also what helps to keep you really stable - it is something I want to try experimenting with and am starting to try just a little bit of cardiovascular - just 15mins of jogging 3 times a week so that I can fit it in and see the results. I also wonder whether you weight can come into it too (just thinking out loud here!) and the length you've had diabetes. I know that I find that when my sugar is in 4s or 5s it takes very little to knock it into hypo, and a quick response to a hypo can save any liver dumps if I can stop it going too low then it doesn't seem to cause me too many problems (and is also what you want to do anyway). Are you going to do your big carb meal in the middle of the day?
I just find that in theory I fit you less than 9 mmol spike but I know my HBA1c will not be anywhere that low - it will be more a 20% difference - so around 6. I have had HBA1cs in the 5s only when I was pregnant and I got to their target but I found it was just too many hypos and I was having to eat lots of wholegrain stuff to avoid post meal peaks and almost eating my food slowly over a period of time just to stop the peaks (I remember saying at the time - to be able to drip feed food with the insulin would be the ideal, but it is hard to do in practise!)…this is just me and my experiences and we are all different and it was a while ago.
I like the maths and it makes sense, part of it reminds me of the olden days of diabetic care where I went through a whole patch of being told my blood sugar should be between these levels and it is so straightforward, and it felt like some doctors believed you just do maths like that and your blood sugar should just float along at the same level (it felt like they had read a text book)….but the reality is that it doesn't just float at 5, but even if it doesn't just float at 5 you can do a lot to keep it within the ball park and still achieve good HBA1cs but it takes lots of work
I do think that when you are serious about sport and exercise from a young age you pay a lot more attention to what you eat as you can see the effects in your performance whereas if you aren't so active you can get a way with not noticing it so much so it sounds like you got trained in some great eating habits 
. In my own experiences I've found (and this may not be same for you) that diabetes nurses/advisors and to some extent doctors will dumb down facts or not disclose all information about carbs and insulin with respect to blood sugar levels to avoid confusing and over-complicating things to new patients so as not to put them off self medicating and to allow them to ease into insulin therapy. However you should eventually start to do your own research and education to truly have 100% control over your average levels to avoid any unnecessary complications in the future.
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