RSS can be polled as frequently or infrequently as you like, it's just a bit of XML hosted by a site which lists content or links to content.

Tracking what's been read or not isn't done by the RSS feed or whoever hosts it, it's performed by the user's feed reader, which be just a local app on your phone or PC, or it might be a cloud service, either hosted (like Feedly) or self-hosted (using ie. FreshRSS).