Priority is a way to group your notification so they can be easier to read in the same filter inboxes.
For each source you can define a priority. The priority does nothing special on the server at the moment. This is just a way for you to group your source by importance relative to your personal needs.
For example, if:
- you set your Twitter account to "low"
- you set priority of a work RSS feed for server alert to "high"
Now, if you create a filter that limit notification to only high priority items, that filter will only contains important items for you to read (based on the priority of the source). The intended usage is that you will start reading all the items from the "important" filter you created to make sure you do not miss anything that matter to you. Then, optionally and as you have time, you can read other inbox filters (like the unread default one for example).
Priority is not a way to define how many alert at most you would like to get from each source. At the moment, it is really about grouping your notifications for easier reading.
So that you better understand the importance of priority, here is the longer term vision. We plan to have a global mode for the user to define his current priority. It will allow to limit the number of alert received to only higher priority items. This is a good way to avoid information overload during week-end for example.