Well, I'm polling my feed reader's default. Which is every 15 minutes. Many RSS feeds for large sites post more than ten stories a day but only show the last ten stories on their feed, so checking regularly is critical.

However, this author specifies I may get IP banned if I check his feed more than once a day: https://cheapskatesguide.org/policy-on-robots.html

Wow that's just... special. WTF?