I am using inoreader (cloudbased), which seems to adjust its polling rate depending on how frequently the feed was updated in the past and how many users are following it. This seems to be between 10 minutes for things like the verge and 60+ minutes for smaller feeds, but I am not sure, if it also takes into account rss header information. The Feed of the blog of this post seems to be refreshed every 6+ hours, but idk why that is.