You are reducing the number of carries. The article explains it clearly. If you're not convinced by the article, I won't try to convince you. (Edit: the last thing I'll add: you are reducing the number of carries for 64-bit additions. When adding 13 51-bit numbers, that does not count as carries instruction-wise, as it's still add, not adc.)
I see what I was doing wrong, I was considering total bit carries during the addition, ie... 1+1= 10 and is a one bit carry, and not the carry operation done after overflowing the word boundary.
Next time, I'll keep from reading tech articles while running on too little sleep.
