The speed of crawling and updating for pages depends more on the UR (URL Rating) metric of a given page than on the overall DR (Domain Rating) of a website.
For instance, let's imagine two websites. The first one has a comparatively low DR of 30, but its individual pages have UR of 20. The second website has a DR of 60 and thousands of pages with lower UR. Naturally, Ahrefs bot will index those pages on the first website faster.