Thanks for sharing @ajtatum! I can see where you are coming from.
Personally I use Miniflux as my RSS Reader which has an API but doesn’t support webhooks unfortunately. However, if you’re fine with polling that’d be extremely easy to implement as the Miniflux API supports a lot of parameters allowing filtering. That way you wouldn’t have to manage a separate database for your posts and also won’t have to pay extra for more than 50 feeds.
If you simply want to process new items every 6 hours, a workflow like this would do the job:
You’d get your posts in a really handy format afterwards:
Of course you can (and probably should) refine this for additional resilience (for example fetch all unread posts and mark all processed posts as read afterwards - this will help in case a feed is down temporarily and comes back only after your polling interval is over).
Perhaps Inoreader offers a similar API? If not, Miniflux might be worth considering - it’s free if you self host ($15 per year when hosted by them) and works really well with n8n as I just found out 
Hope this adds a bit of perspective! If you want to, you could set your polling intervals quite low and could even build your own webhook sending logic in n8n that way.