The ideal number of items in an RSS feed depends on how frequently it is updated and the type of content. For frequently updated feeds, such as news sites, 50 to 60 items ensure relevant content is provided. For less frequent updates, 20 items are often sufficient.
Different RSS versions also affect item limits. RSS 0.91 enforces a 15-item cap, while RSS 1.0 and 2.0 allow an unlimited number of items, 100 items is a good practical limit. The number of items should be tailored to the feed's update frequency and audience needs, with some opting to deliver content from the last 24 hours to ensure timeliness.