I always noticed it in A Song of Ice and Fire but I always assumed it was just one of those fantasy tropes, like having a lot of apostrophes and making everything a pronoun.
By the time Dracula was written in 1897, this custom was entirely out of style in the English speaking world, and that had long been the case. (1, 2, 3, 4.)
Bram Stoker's character, Abraham van Helsing, is supposed to be Dutch. So Stoker here is most likely trying to make the character sound a bit Dutch. The Dutch word for "twenty-nine" is "negenentwintig", literally "nine and twenty". Modern German uses the same convention. "Neunundzwanzig" means "nine and twenty".
If you go back to the 1600s up until about the mid-1700s in English, you sometimes see both conventions side by side. By the time of the Revolutionary War, however, "nine and twenty" was pretty much completely out of style. For example, all, or almost all, writings refer to the year "seventeen seventy six". The term "seventeen six-and-seventy" is pretty much unheard of.
You might want to try r/linguistics.